SUMMARY

This summary highlights selected information contained elsewhere in this prospectus, but it does not contain all of the information that you should consider before deciding to invest in our common stock. You should carefully read the entire prospectus, including the information presented under the section entitled “Risk Factors” and the financial statements and the notes thereto, included elsewhere in this prospectus, before making an investment decision. Some of the statements in the following summary constitute forward-looking statements. See “Special Note Regarding Forward-Looking Statements.” Unless the context otherwise requires, all references in this summary to the “Company,” “Hornbeck,” “HOS,” “we,” “us,” “our” or similar terms refer to Hornbeck Offshore Services, Inc. and its consolidated subsidiaries. Where we present information on an “as-adjusted basis,” it means that such information is presented giving effect to this offering and the use of proceeds therefrom, as reflected in more detail under the captions “Use of Proceeds” and “Capitalization.” Additionally, unless noted otherwise, discussions surrounding our vessels are as of October 31, 2023 and include the two vessels delivered in November 2023 and the one remaining vessel expected to be delivered by December 31, 2023 as part of the ECO Acquisitions #2, but due to supply chain constraints such delivery could extend into early 2024. Such discussions also include two partially constructed Jones Act-qualified MPSV newbuilds to be completed pursuant to our settlement with the Surety, which we expect to be delivered in 2025. Our vessels exclude four OSVs that we operate on behalf of the U.S. Navy.

We have defined certain industry terms used in this document in “Commonly Used Defined Terms” and “Glossary of Terms,” appearing immediately after the Table of Contents to this prospectus.

Company Overview

Hornbeck is a leading provider of marine transportation services to customers in the offshore oilfield market and diversified non-oilfield markets, including military support services, renewable energy development and other non-oilfield service offerings. Since our founding more than 26 years ago, we have focused on providing innovative, technologically advanced marine solutions to meet the evolving needs of our customers across our core geographic regions covering the United States and Latin America. Our team brings substantial industry expertise built through decades of experience and has leveraged that knowledge to amass what we believe is one of the largest, highest specification fleets of Offshore Supply Vessels (“OSVs”) and Multi-Purpose Support Vessels (“MPSVs”) in the industry. Approximately 75% of our total fleet consists of high-spec or ultra high-spec vessels, and we believe we have the number one ultra high-spec market position in the U.S., and the third largest fleet of high-spec and ultra high-spec OSVs in the world, measured by DWT capacity. We own a fleet of 75 multi-class OSVs and MPSVs, 58 of which are U.S. Jones Act-qualified vessels. Our Jones Act-qualified high-spec and ultra high-spec OSVs account for approximately 26% of the total industry supply of such vessels. We opportunistically expand our fleet into new, high-growth, cabotage-protected markets from time to time to enhance our fleet offerings to customers. Our mission is to be recognized as the energy industry’s marine transportation and service Company of Choice^® for our customers, employees and investors through innovative, high-quality, value-added business solutions delivered with enthusiasm, integrity and professionalism with the utmost regard for the safety of individuals and the protection of the environment.

Our fleet of 60 OSVs primarily provides transportation of equipment, materials and supplies to offshore drilling rigs, production platforms, subsea construction projects and other non-oilfield applications. Increasingly, given their versatility, our OSVs are being deployed in a variety of non-oilfield applications including military support services, renewable energy development for offshore wind, humanitarian aid and disaster relief, aerospace and telecommunications. Our OSVs differ from other marine service vessels in that they provide increased cargo-carrying flexibility and capacity that can transport large quantities of deck cargoes as well as various liquid and dry bulk cargoes in below deck tanks providing flexibility for a variety of jobs.

Moreover, our OSVs are outfitted with advanced technologies, including dynamic positioning capabilities, which allows each vessel to safely interface with another offshore vessel, exploration and production facility or an offshore asset by maintaining an absolute or relative position when performing its work.

Our fleet of 15 MPSVs provides commissioning and decommissioning support services, asset construction capabilities, recurring inspection, repair and maintenance services and flotel accommodations. The vessels primarily serve the oil and gas market, with capabilities including the installation of oilfield wellheads, risers, umbilicals, and other equipment placed on the seafloor and other floating production facilities. Further, these vessels are capable of supporting a variety of other non-oilfield offshore infrastructure projects, including the development of offshore windfarms, by providing the equipment and capabilities to support the installation and maintenance of wind turbines and platforms. Because of our ability to serve a diverse set of end markets, MPSV operations are typically less directly linked with the number of active drilling rigs in operation and are therefore less cyclical. Our high- and ultra high-spec OSVs can be contracted alongside our MPSVs on major projects, providing operating efficiencies and pull-through revenue. Most of our MPSVs have one or more deepwater cranes fitted on the deck, deploy one or more Remotely Operated Vehicles (“ROVs”) to support subsea work, and have an installed helideck to facilitate the on-/off-boarding of specialist service providers and personnel. MPSVs can also be outfitted as flotels to provide accommodations, offices, catering, laundry, medical, and recreational facilities to large numbers of offshore workers for the duration of a project. When configured as flotels, our MPSVs have capacities to house up to 245 workers for major installation, maintenance and overhaul projects. Based on overall length and total lifting capacity, the two HOS 400 class MPSVs that are currently under construction are expected to be the largest Jones Act-qualified MPSVs in the market and will have additional capabilities due to their size and sophistication. We are also in the process of converting one of our U.S.-flagged, HOSMAX 280 class OSVs into a dual-use SOV/flotel, which will be capable of providing SOV services to the U.S. offshore wind market. In addition to the services performed by our existing fleet of MPSVs, these three vessels will be equipped with systems that we expect will make them suitable for complex services, including light well intervention and offshore wind farm development, that require larger or more versatile vessels than the fleet of MPSVs currently available in the U.S. market. We expect these three MPSVs to be delivered and placed into active service in 2025.

Our ability to reconfigure or modify vessels in our fleet to meet evolving industry demands and the needs of our customers is critical to our success. This enables us to reconfigure stacked OSVs to service non-oilfield service customers. As offshore activities expand in scope and become increasingly more complex, the demand for high specification, fit-for-purpose equipment and service capabilities has accelerated, creating disproportionate competitive advantages for companies able to adapt vessels and offerings quickly to respond to changing customer needs.

With an average of over 37 years of experience in the marine transportation and service industry and having worked together at Hornbeck for over 20 years, our senior management team has the depth of experience necessary to successfully compete in the offshore vessel business. We have tremendous confidence that both our team and our strategy have been organized in a manner that best positions our Company to effectively execute in this dynamic and demanding operating environment.

Fleet Composition and Operating Regions

Hornbeck owns and operates what we believe is one of the highest specification, most technologically advanced fleets of OSVs and MPSVs in the industry. Our fleet of 75 vessels primarily operates across our core geographic markets of the United States and Latin America. We predominantly serve our oilfield customers in the U.S. GoM, the Caribbean, Northern South America and Brazil, while our vessels primarily serve our non-oilfield customers from the East and West Coasts of the United States and in the U.S. GoM. We operate our Mexican-flagged vessels across the Caribbean and Northern South America when not operated in Mexico,

as well as in other international markets, utilizing a highly-skilled workforce of Mexican mariners that have been trained in our safety systems and culture. A map illustrating our active vessel locations as of October 31, 2023 is below:

OSV Fleet

The following table illustrates our fleet of OSVs and the nations in which they are flagged as of October 31, 2023:

MPSV Fleet

The following table illustrates our fleet of MPSVs and the nations in which they are flagged as of October 31, 2023:

Jones Act and other cabotage laws

Our U.S.-flagged vessels are all Jones Act-qualified. The majority of our U.S. operations are subject to the provisions of the Jones Act which, subject to limited exceptions, restricts maritime transportation of merchandise between points in the U.S. to vessels that are: (a) built in the United States; (b) registered under the U.S. flag; (c) crewed by U.S. citizens or lawful permanent residents; and (d) owned and operated by U.S. citizens within the meaning of the Jones Act. Based on publicly-available information compiled by the Company and data provided by Spinergie, the supply of Jones Act-qualified vessels is limited as there are only 81 active high- and ultra high-spec Jones Act-qualified OSVs in the U.S. GoM as of October 31, 2023. Of this limited supply, Hornbeck owns 23% of the market, representing the second largest such fleet in the industry. Mexico and Brazil each have their own cabotage laws that provide varying levels of insulation from foreign sources of competition that may be unwilling to contribute capital or otherwise satisfy local ownership, crewing, tax and/or build requirements. In 2023, maritime regulators in Mexico implemented new approaches in their oversight of Navieras that historically have permissible levels of non-Mexican ownership, such as ours. As a result, we took legal action in Mexico to preserve our cabotage privileges there. While a stay has been issued and we plan to prosecute our claim seeking permanent reinstatement of our Mexican cabotage privileges, we nevertheless elected to move most of our Mexican-flagged vessels into various non-Mexican international markets utilizing our highly-skilled Mexican mariners and shore-based employees. We expect that these vessels will have the opportunity to work in Mexico as the regulatory landscape for Navieras with non-Mexican ownership stabilizes. These cabotage-protected markets create meaningful barriers to entry for foreign-flagged vessels.

Customer Markets

The OSV and MPSV market has expanded rapidly since the 1970s, driven initially by growing offshore oil and gas production and more recently supported by diversified non-oilfield customer markets including military support services, renewable energy development and other non-oilfield service offerings. In response to changing market conditions and customer demand, we regularly transfer vessels between our core geographic areas and

adapt equipment and features of vessels to best meet potential revenue opportunities. Each customer market has specialized service needs and vessel requirements. For the nine months ended September 30, 2023, approximately 50% of our revenues were attributed to oil and gas drilling support activities. The remaining approximately 50% of our revenues were generated away from the drill bit, comprised of approximately 31% coming from oilfield specialty activities, including offshore construction and equipment installation, as well as decommissioning and plugging and abandonment work; approximately 17% coming from military support services and Humanitarian Aid and Disaster Relief (“HADR”); and approximately 2% coming from other non-oilfield support services, including offshore wind development, construction and support services. As we continue to diversify our customer markets, we expect the non-oilfield markets to contribute a greater portion of revenues in the future.

Oilfield Services

We predominately serve our oilfield customers in the U.S. GoM, the Caribbean, Northern South America and Brazil. Our vessels provide support to offshore oil and gas exploration and production companies in two key areas: (i) oilfield drilling support and (ii) oilfield specialty services. Drilling support provides services that are specifically related to offshore drilling and production activities. This includes the transportation of drilling equipment, such as wellheads and drill pipe, as well as drilling fluids and other bulk products used in the development of new exploration wells and their subsequent production activities. Oilfield specialty services support ongoing or recurring oilfield activities, such as equipment installation services, IRM, flowback, well testing, pipeline flushing, decommissioning, and worker accommodations and transportation. In combination, we offer our oilfield customers a comprehensive range of vessel types and service offerings that cover the entire value chain of offshore hydrocarbon development. Additionally, we operate a port facility located in Port Fourchon, Louisiana, where we are able to stage equipment and cargos in support of such services and can also perform some of our own maintenance, outfitting and other in-the-water shipyard repair activities.

Non-Oilfield Services

Military Support Services

Since our inception, we have been a prominent, private sector service provider to the U.S. military by delivering vessels that support their readiness and security. We support our government customers in two key service offerings primarily from the East and West Coasts of the United States. We provide ongoing operation and maintenance of four highly specialized OSVs (which we previously developed, constructed, and sold to the U.S. Navy) via a long-term Operations & Maintenance (“O&M”) contract. We also own, operate, and charter vessels that provide submarine supply services, rescue and recovery capabilities, transportation services and training drills. Our military service capabilities are an accelerating component of our service portfolio and military support is a customer market that is of particular importance given the stability provided by the U.S. government’s desire to execute long-term service agreements with qualified private contractors. We have received approximately $53.6 million, $65.6 million and $77.1 million of revenue for military support services for the years ended 2021 and 2022 and for the nine months ended September 30, 2023, respectively.

Renewable Energy

Renewable energy, and particularly offshore windfarms and infrastructure, is in its early stage of development in the U.S. and represents an emerging market for our services. Certain of the development and maintenance aspects of U.S. offshore windfarms will require the use of U.S.-flagged, Jones Act-qualified, high specification vessels, for which we are well-positioned to offer our services. We believe that vessels such as ours will be critical across all stages of the offshore windfarm development cycle, including installation support, geophysical survey, vessel support for testing and operations maintenance and repair. Offshore wind development and associated services represent a potential high-growth customer market for our business and our growing involvement positions our business to actively participate in the alternative energy market.

Other Non-Oilfield Services

The versatility of our vessels allows us to support communities in our core geographic areas by providing other non-oilfield services, including humanitarian aid and disaster relief, and service to the aerospace and telecommunications industries. For example, our fleet can support oil spill relief, hurricane recovery, vessel salvage and a broad range of search and rescue operations by deploying vessels to high-need areas in response to natural disasters or crises and providing those affected with lifesaving supplies and equipment. Additionally, our vessels are equipped to support aerospace launches that call for rocket component landing and recovery capabilities.

Collectively, our oilfield and non-oilfield customer markets provide a diverse platform from which we can leverage the capabilities of our vessels and creatively deploy them with customers to serve new markets or high-need service areas. We believe that the diversification benefits that come from servicing a broad range of customers reduces the potential variability in our operating performance.

Industry Overview

Offshore Exploration and Production

Over the last three decades, the offshore oil and gas industry has undergone significant technological change, marked by an ability to explore and produce hydrocarbons in deep and ultra-deepwater regions. These areas contain some of the largest hydrocarbon reserve deposits anywhere in the world with inventory that is expected to last decades.

Most deepwater offshore drilling activity is concentrated in the U.S. GoM, South America (largely dominated by Brazil and more recently, Guyana) and West Africa. Based on Rystad industry data as of September 2023, approximately 74% of global deepwater hydrocarbons are located in the GoM and South America. Moreover, per the Bureau of Safety and Environmental Enforcement (“BSEE”), average deepwater well depths have been on an upward trajectory creating significant demand for high- and ultra high-spec OSVs and MPSVs, which are well-positioned to service larger, more remote projects given their greater storage capacities, larger deck space, and industry-leading technologies.

We expect offshore drilling activity to accelerate through 2025. Offshore activity is economically advantaged with low breakeven prices. Based on Rystad industry data as of September 2023, nearly 90% of offshore proven reserves and probable reserves are economic when crude oil prices are at or below $40.00 per barrel, a level well below 2023 year-to-date prices. As a result, offshore activity is expected to accelerate and Rystad forecasts that offshore rig counts in Hornbeck’s core markets will increase approximately 19% through 2026. Contracted drilling rigs that provide exploration and drilling services to major exploration and development companies are a key leading indicator to OSV demand as each rig working to drill a well requires several OSVs to service it with equipment and supplies. The number of OSVs required to support a drilling rig depends on many factors including the type of drilling activity, the development stage of the well, and the location of the rig. Typically, during the initial drilling stage, more OSVs are required to supply drilling mud, drill pipe, and other materials than at later stages in the drilling cycle. On average, and based on recent trends in active offshore drilling rigs and OSVs, we believe a typical offshore drilling rig requires approximately three to four OSVs to provide ongoing services at any one time with select areas such as Brazil and the Caribbean generally requiring a greater number of OSVs per drilling rig due to greater logistical challenges in those markets resulting in longer vessel turnaround times.

Our fleet of vessels provides logistics support and specialty services to the offshore oil and gas exploration and production industry, primarily in the U.S. GoM, the Caribbean, Northern South America and Brazil, as well as non-oilfield specialty services for the U.S. military and other non-oilfield service customers primarily in the U.S. GoM and from the East and West Coasts of the United States. The United States, Mexico and Brazil have strict cabotage laws that provide us varying levels of insulation from foreign sources of competition that may be

unwilling to contribute capital or otherwise satisfy local ownership, crewing, tax and/or build requirements. We have vessels flagged in each of these jurisdictions and, due to treaties or other legal benefits, we are regularly able to move vessels and/or crews among these jurisdictions.

Below are more detailed descriptions of the industry dynamics impacting our core Oilfield Services operating markets:

U.S. GoM

The U.S. GoM continues to be a world-class basin, attracting significant capital from exploration and production companies. Based on Rystad industry data, U.S. GoM offshore rig counts have increased from 16 to 21 rigs from 2021 to 2023 and are expected to remain range-bound between 20 and 22 rigs through 2027. Similarly, U.S. GoM offshore well counts are expected to increase every year from 2023 through 2027 with an average CAGR of approximately 4.5%. Due to higher cost, greater complexity and longer equipment and permitting lead times compared to conventional onshore drilling, offshore projects are characterized by long cycle planning and investment. This dynamic results in greater stability and resilience through commodity price cycles. Historically, onshore rig counts are more variable during periods of commodity price volatility than offshore rig counts.

The increased focus on the need for low carbon-intensity production has also highlighted the importance of the GoM and its lower global greenhouse gas (“GHGs”) emissions intensity (CO2e/kboe) relative to other global offshore basins. According to Wood Mackenzie’s Emissions Benchmarking Tool, U.S. Gulf of Mexico Deepwater’s weighted average emissions intensity in 2023 is 8.49 tCO2e/kboe compared to a global weighted average of 20.22 tCO2e/kboe. As a result, we believe that the GoM will continue to be an area of increased investment and production by many of the large oil and gas producers.

Brazil

Based on Rystad industry data, Brazil is expected to receive the most deepwater oil and gas investment worldwide between 2024 and 2027. Brazil has seen a significant increase in investment in its upstream resources from private exploration and production companies since the 2014 downturn, when state oil company Petrobras began selective asset sales to address its balance sheet issues. Supported by the current oil price environment, many large international oil companies as well as local independents are investing in deepwater exploration and development activities. Additionally, Petrobras has publicly announced plans to spend approximately $65 billion on exploration and production activities from 2023 through 2027.

Based on Rystad industry data, the offshore rig count in Brazil is forecasted to increase to 30 rigs in 2024, a 20% increase from current levels. In addition, Rystad industry data anticipates rig count levels remaining above 2024 levels through at least 2027. The increase in activity will likely require additional vessels to mobilize to the area to support this increased drilling activity. As of October 31, 2023, four U.S. Jones Act high- and ultra high-spec vessels have relocated from the U.S. GoM to Brazil in order to fulfill the current demand in the region.

Caribbean and Northern South America

The Caribbean and Northern South America are developing markets for deepwater exploration and production. Activity in the region is primarily focused in the Guyana-Suriname basin, but also includes Colombia, Trinidad and occasionally other Caribbean islands. Due to the proximity to the U.S. GoM and the

Mexico GoM and the offshore operating environment, high-spec and ultra high-spec U.S.-flagged and Mexico-flagged OSVs are ideally suited to serve customers in this region. Currently, over 50% of the OSVs operating in the area are U.S.-flagged.

Since the discovery of the Liza-1 well in 2015, the Guyana-Suriname basin has become one of the fastest growing deepwater exploration markets in the world. In April of 2022, ExxonMobil announced the final investment decision, or FID, for the Yellowtail development offshore Guyana, which was the fourth, and largest, project in the Staebroek Block. The total investment is expected to reach $12 billion and deliver a daily output of 250,000 barrels a day. According to published data from Hess Corporation as of March 2023, ExxonMobil’s partner in the Yellowtail development, the Staebroek Block’s gross discovered recoverable resource estimate is more than 11 billion barrels of oil equivalent. Other operators, such as TotalEnergies, have announced plans to invest in the region with a FID for Block 58 in Suriname expected to be approved in 2023.

As of October 31, 2023, there were eight offshore rigs operating in this region. According to Rystad industry data, this number is expected to increase to nine offshore rigs and remain at this increased level through at least 2027. These activity levels will require additional vessels to mobilize to the area to support drilling activity. We believe that additional U.S.-flagged vessels are well-suited to support these new drilling programs. As of October 31, 2023, 19 U.S. Jones Act high- and ultra high-spec vessels have relocated from the U.S. GoM to the Caribbean and South America in order to fulfill the current demand in this region.

Non-Oilfield Services

Beyond Oilfield Services, our vessels are actively involved in the support of critical offshore activities in our core geographic regions, including military services, renewable energy development and other non-oilfield service offerings. As of October 31, 2023, 15 U.S. Jones Act-qualified high- and ultra high-spec vessels were working in military, offshore wind, aerospace or other industries. These non-oilfield markets have had a material impact on an already tight U.S. Jones Act market. Below are more detailed descriptions of the industry dynamics within each of those customer markets:

Military Support Services

The United States has relied on private vessel owners and operators comprising the U.S. Merchant Marine to provide vessels that support U.S. military readiness and security, as well as peacetime and wartime services. We provide such support primarily from the East and West Coasts of the United States. The use of specialized vessels, including OSVs and MPSVs, has increased as the broad utility of these vessels has been recognized by government customers, particularly the U.S. Navy. We believe the opportunities for additional military use could include:

Military support services represent a tremendous growth opportunity beyond the oilfield. Military business provides a diversified customer market that counterbalances oilfield volatility and generally comes with longer tenor contracts (generally more than three years). We continue to grow our military support services offerings and expect them to continue to grow in the future.

Renewable Energy Development

The offshore wind market is in its early stage of development and shows potential as an emerging market for our services in the U.S. GoM, as well as certain areas on the East and West Coasts of the United States. Field

surveying, construction and operation for offshore wind require many of the core competencies and vessel specifications used in oilfield services, creating opportunities for legacy oilfield vessel providers to service this market. Moreover, many of the wind farms developed in domestic U.S. waters will require Jones Act-qualified vessels thereby creating cabotage protections for this work.

Vessel requirements for offshore wind development typically span three distinct phases:

The U.S. offshore wind market is forecasted to grow. In 2021, the Biden Administration released its Offshore Wind Energy Strategy outlining its goal of deploying 30 gigawatts of offshore wind in the United States by 2030. Based on the DoE Report, estimated installations of U.S. offshore wind assets are expected to accelerate from approximately 130 megawatts in 2023 to approximately 6,500 megawatts in 2027. According to the BOEM, 59 wind energy lease areas have been identified along U.S. coastlines and the Great Lakes with more than 50 locations already having named lease holders. Of that, 21 offshore wind projects have already been sanctioned along the U.S. East Coast with more expected as the U.S. economy attempts to transition its energy mix to a higher percentage of renewable energy sources. Additionally, five lease sales on the West Coast of the United States are expected to require floating installation capabilities and vessels which Hornbeck’s fleet is capable of providing.

Other Non-Oilfield Services

We have multiple areas of growth in other non-oilfield services including:

Our Competitive Strengths

Leading presence in the United States and Latin America

Hornbeck was established in 1997 and has one of the most capable and high-spec fleets of vessels in the industry. Based on publicly-available information compiled by the Company and data provided by Spinergie, we

believe that our fleet of 41 high-spec and ultra high-spec OSVs, totaling 217,184 in DWT capacity, represents 6.3% of the 3,429,535 total DWT of such vessels in the world, making Hornbeck the third largest fleet out of 169 companies that own and operate high-spec and ultra high-spec OSVs worldwide. Furthermore, we believe that our fleet of 14 U.S.-flagged ultra high-spec OSVs, totaling 83,250 in DWT capacity, represents the largest fleet of such vessels operating in the United States measured by DWT capacity. Additionally, we are one of the top operators of OSVs, based on DWT, in each of our two core geographic markets, which include 2,424,266 DWT and constitute 41.3% of the global supply of 5,864,666 DWT to such markets. Our 46 U.S.-flagged OSVs, totaling 206,806 in DWT capacity, comprise the second largest fleet of technologically advanced, OSVs qualified for work in the U.S. GoM under the Jones Act. As of October 31, 2023, our active fleet of OSVs and MPSVs consisted of (i) 18 U.S.-flagged OSVs and seven MPSVs in the U.S. GoM, (ii) four OSVs and one MPSV in the U.S. Atlantic, (iii) one OSV and two MPSVs in the U.S. Pacific, (iv) five OSVs in offshore Brazil, (v) four OSVs and one MPSV in the Caribbean and Northern South America and (vi) one OSV in offshore Africa. We believe that having scale in our core markets with the flexibility to transfer vessels among regions benefits our customers and provides us with operating efficiencies.

Large and diverse fleet of technologically advanced high-spec vessels

Over the past 26 years, we have assembled a multi-class fleet of 60 OSVs and 15 MPSVs. Since 2014, we have focused on expanding our line of high-spec and ultra high-spec vessels, increasing our fleet of such vessels from 41% of our fleet in 2014 to 75% of our fleet in 2023. These high-spec and ultra high-spec vessels incorporate sophisticated technologies, are designed specifically to operate safely in complex and challenging environments and are equipped with specialty equipment and other features to respond to the needs of our customers through the project development and operation lifecycle. These technologies include dynamic positioning, roll reduction systems and controllable pitch thrusters, which allow our vessels to maintain position with minimal variance, and our cargo handling systems, which permit high volume transfer rates of liquid mud and dry bulk materials. In addition, we are able to outfit our vessels with specialty equipment and certain features as needed for specific projects. The greater fuel efficiency, larger carrying capacity size, advanced mud-handling systems and other high-spec features that reduce project downtime create a compelling value proposition. As a result, we believe that we earn higher average day-rates when compared to our competitors. According to industry data from Fearnley Offshore Supply, our average dayrates were 58%, 87%, and 48% higher than those of comparably sized vessels owned by other operators in 2021, 2022, and the nine months ended September 30, 2023, respectively.

Strong market position due to qualification under the Jones Act and favorable sector tailwinds

As a leader in marine transportation services to the offshore oilfield industry, we believe Hornbeck is well-positioned to capitalize on favorable industry conditions for significant growth opportunities, particularly in offshore wind development and support services to the U.S. military on the East and West Coasts of the United States. The United States has strict cabotage laws that provide some insulation from foreign sources of competition. In addition, the U.S. high-spec and ultra high-spec vessel supply is highly restricted with long lead times for new construction. High newbuild costs result in unfavorable economics for newbuilds, which is exacerbated by limited pools of available capital to make investments into new fleet construction. We believe our reputation for high-quality, safe and reliable operations, complex problem solving, operational flexibility, and world-class vessels allows Hornbeck to compete effectively for and retain qualified mariners, which positions Hornbeck for long-term sustainable growth in a tight labor market. In addition, our robust offering of services, ranging from initial construction to decommissioning, has allowed us to compete effectively and remain a trusted service provider for active offshore companies as well as the U.S. military.

Successful track record of strategic vessel acquisitions

We have built our fleet through a combination of new builds and strategic acquisitions from other operators. Our management team’s extensive naval architecture, marine engineering and shipyard experience has enabled us to quickly integrate newly acquired vessels into our fleet and retrofit them to meet our quality standards and customer needs cost-effectively. From time to time, we consider opportunistic acquisitions of single vessels, vessel fleets, and businesses that strategically complement our existing operations to enable us to grow our business and better serve our customers. Since 2017, we have successfully completed and have agreements to acquire 19 vessels, 13 of which are currently operating as part of our high-spec fleet and six of which are yet to be placed in service or delivered.

Diversified service offerings and customer markets provide stability to cash flows

We have well-established relationships with leading oilfield and non-oilfield companies and the U.S. government and believe such relationships are in part maintained because of our diversified service offerings in the oilfield and non-oilfield customer markets. Our diversified service offerings allow us to pivot based on our customers’ needs and gives our customers confidence to commit to longer-term contracts for our services, which provides us with cash flow stability. Additionally, these large, integrated customers are financially stable and can better withstand economic or market downturns in a volatile market, and we believe maintaining relationships with these customers will ultimately result in better visibility to vessel utilization and greater liquidity for us in the future.

Experienced management team with proven track record

Our founder-led executive management team has an average of over 37 years of domestic and international marine transportation industry-related experience and has worked together at the Company for over 20 years. Our team is comprised of individuals with extensive, global experience with backgrounds across many diverse fields including engineering, project management, military service, finance, accounting and corporate leadership. We believe that our team has successfully demonstrated its ability to grow our fleet through new construction and strategic acquisitions and to secure profitable contracts for our vessels in both favorable and unfavorable market conditions in domestic and foreign markets.

Attractive growth opportunities

Our fleet of technologically advanced high-spec and ultra high-spec vessels is increasingly being deployed to serve the accelerating needs of the U.S. Military, renewable energy, and aerospace industries. These high-growth markets require U.S.-flagged Jones Act-qualified vessels, which can be custom tailored to address a broad spectrum of services. For these applications, our vessels are typically contracted for greater than three years, providing a counter-balance to cyclicality experienced in our oilfield segments.

Our Strategy

Leverage our geographic presence in the United States and Latin America and grow industry leading service capabilities

We have strategically chosen to focus our efforts in two core geographic markets, the United States and Latin America. While the U.S. GoM will continue to be a priority for us, in recent years we expanded our presence in each of the Mexico GoM, the East and West Coasts of the United States, the Caribbean, Northern South America and Brazil as we anticipate long-term growth in those markets. Given the relative proximity of these markets, we are able to readily move our vessels among them and retain flexibility to relocate those vessels back to U.S. GoM. We believe this will allow us to conduct a more thorough on-going alternative analysis for

vessel deployments among such markets and, thus, better manage our portfolio of contracts to enhance dayrates and utilization over time as contracting opportunities arise. Our Jones Act-qualified high-spec and ultra high-spec OSVs account for approximately 26% of the total industry supply of such vessels. Our vessels have been adapted to operate in a range of oilfield specialty configurations, including flotel services, extended-reach well testing, seismic, deepwater well stimulation, other enhanced oil recovery activities, high pressure pumping, deep-well mooring, ROV support, subsea construction, installation, IRM work and decommissioning services. We are also growing our diverse non-oilfield specialty services, such as military applications, offshore wind farms, oceanographic research, telecommunications, and aerospace projects.

Pursue differentiated customer offerings to optimize utilization and free cash flow generation

We seek to balance and diversify our service offerings to customers, to optimize our vessel utilization and stabilize our free cash flow generation. For example, in addition to our long-term charters in oilfield services and with military and renewable energy customers that contribute to contracted backlog and provide utilization stability, we also seek out short-term charters such as spot oilfield services that typically have higher dayrates. This contracting strategy balances our financial profile between longer-term charters and the flexibility to capture current market dayrates for a portion of our fleet. Our current contracting approach allows us to consistently perform well against our OSV peers when comparing average OSV dayrates and gross margins. The flexibility of our vessel capabilities is designed to optimize our utilization and allows us to pivot in response to market conditions and customer needs, which can lead to more stable free cash flow generation.

Apply existing, and develop new, technologies to meet our customers’ vessel needs and expand our fleet offerings

Our in-house engineering team has been instrumental in applying existing, and developing new, technologies that meet our customers’ vessel needs and provide us with the opportunity to enter new customer markets. For instance, our OSVs and MPSVs are designed to meet the higher capacity and performance needs of our oilfield clients’ increasingly complex drilling and production programs and the diverse needs of our U.S. military, renewable energy and humanitarian aid and disaster relief customers. Further, we are able to reconfigure or retrofit existing assets with existing or new technology to participate in new customer markets such as offshore wind, aerospace and telecommunications. Specifically, we are currently deploying capital to upgrade certain of our vessels to dual service capabilities to better service the oilfield services market as well as the emerging offshore wind market. We remain committed to applying existing and developing new technologies to maintain a technologically advanced fleet that will enable us to continue to provide a high level of customer service and meet the developing needs of our customers.

Focus on selective acquisitions that are strategically and financially accretive

We seek to opportunistically grow our fleet through strategic and financially accretive acquisitions. Our screening criteria focuses on expanding the depth and breadth of our fleet mix as well as diversifying service offerings in our core markets. From time to time, we consider opportunistic acquisitions of single vessels, vessel fleets, and businesses that strategically complement our existing operations to enable us to grow our business and better serve our customers. For example, we recently entered into separate definitive vessel purchase agreements to acquire 12 high-spec OSVs, which we refer to as the ECO Acquisitions.

Maintain a conservative balance sheet, disciplined growth, and robust free cash flow generation through cycles

We adhere to financial principles designed to maintain a conservative balance sheet, disciplined growth, and robust free cash flow generation. Our balance sheet strategy targets less than 1.0x leverage with ample excess liquidity available to withstand industry cycles or take advantage of disciplined growth opportunities.

Our growth strategy involves a disciplined screening of opportunities for differentiated assets that create competitive advantages and is focused on returns and payback periods. Our cash flow generation abilities are centered around maintaining flexible costs and lean organizational structures that seek efficiencies through continuous operational improvement and working capital management.

Continued commitment to sustainability and safety

Safety is of great importance to us and offshore operators due to the environmental and regulatory sensitivity associated with offshore drilling and production activity and wind development. We believe certain of our efforts, such as adopting shipboard energy efficiency management plans, installing emission monitoring systems and pursuing other operational efficiencies, have been successful, allowing us to meet our customers’ needs while supporting our efforts to reduce our emissions of GHG. Additionally, since 2020, our focus on safely addressing operational risk has contributed to maintaining an industry-low total recordable incident rate. Our most recent 5-year average Total Recordable Incident Rate (“TRIR”) was 0.10, outperforming peer averages from the International Marine Contractors Association (“IMCA”) and International Support Owners Association (“ISOA”). Further, in addition to industry standard certifications, as part of our commitment to safety and quality, we have voluntarily pursued and received certifications and classifications that we believe are not generally held by other companies in our industry. We believe that customers recognize our relentless commitment to safety, which contributes to our positive reputation and competitive advantage.

Recent Developments

Resumption of MPSV Newbuild Construction

In October 2023, the Company entered into a final settlement agreement with the Surety and Gulf Island. Pursuant to the settlement agreement, Gulf Island released all claims asserted against the Company and the Company released its claims against Gulf Island and the Surety. Further, the Surety agreed to take over and complete the construction of the two U.S.-flagged, Jones Act-qualified, HOS 400 class MPSVs at a shipyard acceptable to the Company. The Company is obligated to pay only the remaining portion of the original shipyard contract price for the two MPSVs, which amounts to $53.8 million in the aggregate. The Surety is required to cure all defaults of Gulf Island and pay all completion costs in excess of the $53.8 million remaining contract price, excluding approved change orders. The Company expects to incur an additional $30.0 million in the aggregate for discretionary enhancements to add secondary cranes to both vessels. Pursuant to the settlement, the Surety is required to deliver both MPSVs in 2025.

Repayment of Replacement First Lien Term Loans

In August 2023, the Company fully repaid the $68.7 million outstanding principal balance of the Replacement First Lien Term Loans and terminated the First Lien Credit Agreement. As a result, the Company recorded a $1.2 million loss on early extinguishment of debt, primarily related to the write-off of associated deferred issuance costs and original debt issue discount.

ECO Acquisitions

ECO Acquisitions #1

On January 10, 2022, the Company entered into separate definitive vessel purchase agreements with certain affiliates of ECO to acquire up to ten high-spec, 280 class DP-2 OSVs for an aggregate price of $130.0 million. In November 2022, ECO exercised an option to terminate the vessel purchase agreements relating to the last four vessels. ECO refunded initial deposits of $1.5 million in the aggregate and paid an additional amount equal to such deposits as a termination fee. After accounting for such terminations and certain purchase price adjustments,

the aggregate purchase price for the ECO Acquisitions #1 was $82.4 million. Pursuant to the purchase agreements, final payment and the transfer of ownership of each of the vessels occurred on the date of delivery and acceptance for such vessel following the completion of reactivation and regulatory drydockings by ECO. The Company took delivery of the first four vessels between May and December 2022. The Company took delivery of the remaining two vessels from ECO in April and August 2023, respectively.

As of September 30, 2023, the Company had paid $82.2 million on the original purchase price and $1.7 million in purchase price adjustments associated with discretionary enhancements of the ECO Acquisitions #1 vessels, prior to the effect of the $1.5 million termination fee paid by ECO. In addition, the Company had incurred $4.2 million of costs associated with additional outfitting of the six vessels through the third quarter of 2023. The Company expects to incur an additional $0.6 million related to post-closing modifications of the sixth vessel during the fourth quarter of 2023. See “Management’s Discussion and Analysis of Financial Condition and Results of Operations—Liquidity and Capital Resources—Capital Expenditures.”

ECO Acquisitions #2

On December 22, 2022, the Company executed a controlling purchase agreement with Nautical. Pursuant to the controlling purchase agreement, the Company subsequently entered into separate, individual vessel purchase agreements to acquire six high-spec OSVs from Nautical for $17.0 million per vessel. The Nautical vessels are U.S.-flagged, Jones Act-qualified, 280 class DP-2 OSVs with cargo-carrying capacities of circa 4,750 DWT. Nautical is required to complete regulatory drydocking and reactivation activities for each vessel prior to closing. Payment of 10% of the purchase price for each vessel has been paid upon arrival of such vessel to the shipyard and the remaining 90% has been or will be paid at closing and delivery of each vessel. The closing of the first five vessel purchases occurred one at a time in serial deliveries and delivery of the sixth vessel is expected to be completed by December 31, 2023, but due to supply chain constraints such delivery could extend into early 2024. In addition to the aggregate purchase price of $102.0 million, the Company expects to incur an additional $9.3 million related to the outfitting and discretionary enhancement of these six vessels.

During the third quarter of 2023, the Company took delivery of the first two vessels and paid $15.3 million each for the remaining 90% of the original purchase price and $0.2 million per vessel for purchase price adjustments related to discretionary enhancements completed in the shipyard by Nautical. As of September 30, 2023, the Company had paid $40.8 million toward the original purchase price and $0.4 million in purchase price adjustments associated with discretionary enhancements for the ECO Acquisitions #2 vessels. In addition, the Company had incurred $2.3 million of costs associated with additional outfitting of the six vessels through the third quarter of 2023.

In October 2023, the Company took delivery of the third vessel and paid $15.3 million for the remaining 90% of the original purchase price and $0.1 million for purchase price adjustments related to discretionary enhancements. As of October 31, 2023, the Company expected to incur the remaining purchase price of $45.9 million and $6.9 million related to additional outfitting and discretionary enhancements during the fourth quarter of 2023 with respect to the two vessels delivered in November 2023 and assuming the one remaining vessel is delivered by December 31, 2023.

Ongoing Acquisition/Investment Activities

We regularly evaluate additional acquisition opportunities and frequently engage in discussions with potential sellers. We are currently focused on pursuing acquisition opportunities that will further diversify our vessel holdings and the specialty services we offer. The timeline required to negotiate and close on any one or more acquisition opportunities is at times unpredictable and can vary greatly.

Our acquisitions may require material investments and could result in significant modifications to our capital plans, both in the aggregate amount of capital expenditures to be made and a reallocation of capital. Our acquisitions (including the ECO Acquisitions) are typically made for a purchase price which historically we have funded with a combination of borrowings, cash generated from operations and debt and/or equity issuances.

We typically do not announce a transaction until after we have executed a definitive agreement. In certain cases, in order to protect our business interests or for other reasons, we may defer public announcement of a transaction until closing or a later date. Past experience has demonstrated that discussions and negotiations regarding a potential transaction can advance or terminate in a short period of time. Moreover, the closing of any transaction for which we have entered into a definitive agreement may be subject to customary and other closing conditions, which may not ultimately be satisfied or waived. Accordingly, we can give no assurance that our current or future acquisition or investment efforts will be successful.

Risk Factors Summary

Our business is subject to numerous risks and uncertainties, including, but not limited to, those highlighted in the section titled “Risk Factors” and summarized below. We have various categories of risks, including risks relating to our business; risks relating to legal, regulatory, accounting and tax matters; risks relating to our indebtedness; and risks relating to this offering and ownership of our common stock, which are discussed more fully in the section titled “Risk Factors.” As a result, this risk factor summary does not contain all of the information that may be important to you, and you should read this risk factor summary together with the more detailed discussion of risks and uncertainties set forth in the section titled “Risk Factors.” These risks include, but are not limited to, the following:

Risks Relating to Our Business

Risks Relating to Our Legal, Regulatory, Accounting and Tax Matters

Risks Relating to Our Indebtedness

Risks Related to this Offering and Ownership of Our Common Stock

Additional risks, beyond those summarized above or discussed elsewhere in this prospectus, may apply to our business, activities or operations as currently conducted or as we may conduct them in the future or in the markets in which we operate or may in the future operate.

If we are unable to adequately address these and other risks we face, our business, results of operations, financial condition and prospects may be harmed. You should carefully consider all of the information set forth in this prospectus and, in particular, should evaluate the specific factors set forth under “Risk Factors” in deciding whether to invest in our common stock.

Organizational Structure

The following diagram illustrates our organizational structure after giving effect to this offering and the application of proceeds therefrom.

Our Principal Stockholders

Our principal stockholders consist of our three largest stockholders (funds, investment vehicles or accounts managed or advised by Ares, Whitebox or Highbridge or their respective affiliates), who currently collectively own 63.6% of our common stock and 85.9% of our Jones Act Warrants, which are convertible under certain circumstances into 9,767,165 shares of our common stock. On a diluted basis, after giving effect to the conversion of these Jones Act Warrants and this offering and the application of proceeds therefrom, the principal stockholders would own         % of our common stock.

Ares Management Corporation (NYSE: ARES) (“Ares”) is a leading global alternative investment manager offering clients complementary primary and secondary investment solutions across the credit, private equity, real estate and infrastructure asset classes. Ares seeks to provide flexible capital to support businesses and create

value for its stakeholders and within its communities. By collaborating across its investment groups, Ares aims to generate consistent and attractive investment returns throughout market cycles. As of September 30, 2023, Ares’ global platform had approximately $395 billion of assets under management, with approximately 2,800 employees operating across North America, Europe, Asia Pacific and the Middle East.

Whitebox Advisors LLC (“Whitebox”) is a multi-strategy alternative asset manager that seeks to generate optimal risk-adjusted returns for a diversified base of public institutions, private entities and qualified

individuals. Founded in 1999, Whitebox invests across asset classes, geographies, and markets through the hedge fund vehicles and institutional accounts that it advises. The firm maintains offices in Minneapolis, Austin,

New York, London and Sydney.

Highbridge Capital Management (“Highbridge”) is a global alternative investment firm offering credit and volatility focused solutions across a range of liquidity and investment profiles, including hedge funds, drawdown

vehicles, and co-investments. Highbridge manages capital for sophisticated investors, which include financial institutions, public and corporate pension funds, sovereign wealth funds, endowments, and family offices. Highbridge is headquartered in New York, with a research presence in London. Highbridge is an indirect subsidiary of J.P. Morgan Chase & Co.

We use the term “principal stockholders” in this prospectus to describe certain funds, investment vehicles or accounts managed or advised by Ares, Whitebox or Highbridge or their respective affiliates that own shares of our common stock.

Company Corporate Information

Hornbeck Offshore Services, Inc. was incorporated under the laws of the State of Delaware on June 2, 1997. Our principal executive offices are located at 103 Northpark Boulevard, Suite 300, Covington, LA 70433, and our telephone number is (985) 727-2000. Our website address is www.hornbeckoffshore.com. Information contained on, or that can be accessed through, our website is not part of and is not incorporated by reference into this prospectus, and you should not consider information on our website to be part of this prospectus.

The Offering

Unless otherwise indicated or the context otherwise requires, all information in this prospectus reflects and assumes the following:

Additionally, the number of shares of our common stock to be outstanding after this offering is based on shares of our common stock outstanding as of September 30, 2023 and does not reflect:

Summary Historical Financial and Other Data

The summary consolidated statement of operations data for the nine months ended September 30, 2023 and 2022 have been derived from our Quarterly Financial Statements included elsewhere in this prospectus. The summary consolidated statement of operations data for the year ended December 31, 2022, the year ended December 31, 2021, for the period from September 5, 2020 to December 31, 2020 (Successor), and for the period from January 1, 2020 to September 4, 2020 (Predecessor), when our Predecessor emerged from bankruptcy, are derived from our Annual Financial Statements included elsewhere in this prospectus.

Our historical results are not necessarily indicative of the results to be expected in any future period. You should read the following summary financial and other data in conjunction with the sections titled “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and our Financial Statements and related notes included elsewhere in this prospectus.

Non-GAAP Financial Measures

We disclose and discuss EBITDA, Adjusted EBITDA and Adjusted Free Cash Flow as non-GAAP financial measures in this prospectus. We define EBITDA as earnings (net income or loss) before interest, income taxes, depreciation and amortization. Adjusted EBITDA reflects certain adjustments to EBITDA for gains or losses on early extinguishment of debt, terminated debt refinancing costs, stock-based compensation expense and interest income. In addition, Adjusted EBITDA excludes non-cash gains or losses on the fair value adjustment of liability-classified warrants, as well as restructuring costs and reorganization items, net related to the Company’s voluntary relief in 2020 under Chapter 11 of the U.S. Bankruptcy Code and the application of fresh-start accounting under ASC 852, Reorganizations. We define Adjusted Free Cash Flow as Adjusted EBITDA less cash paid for deferred drydocking charges, maintenance capital improvements and non-vessel capital expenditures, cash paid for interest and cash paid for (refunds of) income taxes. Our measures of EBITDA, Adjusted EBITDA and Adjusted Free Cash Flow may not be comparable to similarly titled measures presented by other companies. Other companies may calculate EBITDA, Adjusted EBITDA and Adjusted Free Cash Flow differently than we do, which may limit their usefulness as comparative measures.

We view EBITDA, Adjusted EBITDA and Adjusted Free Cash Flow primarily as liquidity measures and, as such, we believe that the GAAP financial measure most directly comparable to those measures is cash flows

provided by operating activities. Because EBITDA, Adjusted EBITDA and Adjusted Free Cash Flow are not measures calculated in accordance with GAAP, they should not be considered in isolation or as a substitute for operating income, net income or loss, cash flows provided by operating, investing and financing activities, or other income or cash flow statement data prepared in accordance with GAAP. Additionally, Adjusted Free Cash Flow does not represent the total increase or decrease in our cash balance, and it should not be inferred that the entire amount of Adjusted Free Cash Flow is available for dividends, debt or share repurchases or other discretionary expenditures, since we have non-discretionary expenditures that are not deducted from this measure.

EBITDA, Adjusted EBITDA and Adjusted Free Cash Flow are widely used by investors and other users of our financial statements as supplemental financial measures that, when viewed with our GAAP results and the accompanying reconciliations, we believe provide additional information that is useful to gain an understanding of the factors and trends affecting our ability to service debt, pay taxes and fund drydocking charges, maintenance capital improvements and non-vessel capital expenditures. We also believe the disclosure of EBITDA, Adjusted EBITDA and Adjusted Free Cash Flow helps investors or lenders meaningfully evaluate and compare our cash flow generating capacity from quarter to quarter and year to year.

EBITDA, Adjusted EBITDA and Adjusted Free Cash Flow are also financial metrics used by management as supplemental internal measures for planning and forecasting overall expectations and for evaluating actual results against such expectations; for short-term cash bonus incentive compensation purposes; to compare to the EBITDA, Adjusted EBITDA and Adjusted Free Cash Flow of other companies when evaluating potential acquisitions; and to assess our ability to service existing fixed charges and incur additional indebtedness. Additionally, we have historically made certain adjustments to EBITDA to internally evaluate our performance based on the computation of ratios used in certain financial covenants of our credit agreements with various lenders, whenever applicable. Currently, the Company’s Second Lien Credit Agreement includes an incurrence test for the issuance of unsecured debt. The test requires a fixed charge coverage ratio of at least 2.0 to 1.0 at the time any unsecured debt is incurred. The fixed charge coverage ratio is calculated using certain adjustments to EBITDA defined by the Second Lien Credit Agreement, which adjustments are consistent with those reflected in Adjusted EBITDA in this prospectus. In addition, we believe that, based on covenants in prior credit facilities, future debt arrangements may require compliance with certain ratios that will likely include EBITDA or Adjusted EBITDA in the computations. Adjusted EBITDA is also currently utilized in connection with the Company’s short-term cash bonus incentive compensation programs.

The following tables reconcile cash flows provided by (used in) operating activities to EBITDA, Adjusted EBITDA and Adjusted Free Cash Flow, as we define those terms, for the nine months ended September 30, 2023 and 2022, and the year ended December 31, 2022 (Successor), the year ended December 31, 2021 (Successor), the period from September 5, 2020 through December 31, 2020 (Successor) and the period from January 1, 2020 through September 4, 2020 (Predecessor), respectively:

The following table provides the detailed components of EBITDA, Adjusted EBITDA and Adjusted Free Cash Flow as we define those terms, for the nine months ended September 30, 2023 and 2022, and the year ended December 31, 2022 (Successor), the year ended December 31, 2021 (Successor), the period from September 5, 2020 through December 31, 2020 (Successor) and the period from January 1, 2020 through September 4, 2020 (Predecessor), respectively (in thousands):

Set forth below are the material limitations associated with using EBITDA, Adjusted EBITDA and Adjusted Free Cash Flow as non-GAAP financial measures compared to cash flows provided by operating activities:

Management compensates for the above-described limitations in using EBITDA, Adjusted EBITDA and Adjusted Free Cash Flow as non-GAAP financial measures by only using EBITDA, Adjusted EBITDA and Adjusted Free Cash Flow to supplement our GAAP results.

Other Operating Data