Why the Largest Offshore Construction Companies Matter
When we talk about the largest offshore construction companies, we’re not just talking about revenue. Scale in this industry is defined by a combination of financial stability, project backlog, specialised fleet, and technical execution capability. From laying ultra-deep pipelines and installing floating platforms, to building massive offshore wind farms, these companies are the backbone of global offshore energy.
Having worked around offshore yards and vessels, I know firsthand that size translates into reliability. A small contractor can deliver niche scopes, but when billions of dollars and thousands of offshore workers are involved, only the largest offshore construction companies can manage the complexity safely and on schedule.
Below, I break down the top 5 largest offshore construction companies in the world, with insider-style descriptions of their strengths, assets, and why they dominate the global market.
Saipem7 – One of the Largest Offshore Construction Companies After a Historic Merger
Starting with the beginning of 2025, Saipem and Subsea7 merged to create Saipem7, instantly making it one of the largest offshore construction companies in the world and for sure the main player on the market. This merger combined Saipem’s strong onshore and offshore EPC capabilities with Subsea7’s subsea engineering and fleet power, however as well Saipem has a large fleet of modern vessels, one of the biggest I would say.
- Revenue & backlog: Saipem alone had over €14.5 billion in 2024 revenues, and Subsea7 brought a multi-billion subsea backlog. Together, Saipem7 manages projects worth tens of billions – leader on the market.
- Fleet & capabilities: The new group controls S-lay and J-lay pipelay vessels, heavy-lift assets, and subsea construction vessels. This means they can execute entire projects – from deepwater subsea fields to LNG pipelines – under a single contract – there is no other company at this time to cover all this aspects.
- Why it matters: Oil and gas operators prefer fewer contract interfaces. With Saipem7, topside fabrication, subsea installation, hook-up, and commissioning can all be handled by one contractor.
For megaprojects in LNG or deepwater gas, Saipem7 now sets the standard among the largest offshore construction companies.
TechnipFMC – Subsea Systems Specialist Among the Largest Offshore Construction Companies
TechnipFMC has long been one of the largest offshore construction companies because of its subsea production systems and integrated installation services on this market sector.
- Subsea hardware leadership: TechnipFMC designs and supplies subsea trees, manifolds, umbilicals, and flexible flowlines, while also installing them with its own vessels.
- Revenue & backlog: The company reports a strong backlog running into tens of billions, supported by quarterly revenues in the billions.
- Fleet strength: With reel-lay, flexible-lay, and subsea construction vessels, TechnipFMC executes some of the most complex deepwater tie-backs.
If your project revolves around subsea complexity – multiple wells, high-pressure trees, or long-distance tie-backs – TechnipFMC is often the safest choice among the largest offshore construction companies.
Allseas – Heavy-Lift and Pipelay Giant Among the Largest Offshore Construction Companies
Allseas is unique. Unlike many public competitors, it is privately owned but still ranks among the largest offshore construction companies because of its unrivaled fleet. Allseas has the largest vessel in the offshore construction sector.
- Pioneering Spirit: The largest construction vessel in the world, capable of single-lift platform removals and installations exceeding 48,000 tonnes.
- Specialisation: Allseas dominates ultra-heavy S-lay pipelay and decommissioning. Few others can rival its capacity for laying large-diameter trunklines.
- Why clients choose them: When you need one vessel to install or remove a massive topside in a single operation, Allseas is the only option.
Although smaller in revenue, Allseas’ assets give it a spot among the largest offshore construction companies globally.
Boskalis – Marine Works Leader Among the Largest Offshore Construction Companies
Royal Boskalis Westminster is best known for dredging, but its offshore energy division makes it one of the largest offshore construction companies active in both oil & gas and renewables.
- Capabilities: Rock placement, seabed intervention, cable-lay, and foundation installation.
- Fleet: Boskalis operates fall-pipe vessels, heavy-lift assets, dredgers, and cable-lay ships.
- Market focus: A dominant player in offshore wind, performing scour protection, trenching, and foundation installation for major wind farms.
Because modern offshore energy increasingly involves renewables, Boskalis secures its place among the largest offshore construction companies in 2025.
DEME Group – Offshore Renewables and EPC Expansion
DEME Group has expanded aggressively into offshore renewables, pushing it into the ranks of the largest offshore construction companies.
- 2024 results: Turnover of €4.1 billion and a record orderbook over €8 billion.
- Capabilities: Foundation installation, export cable-laying, seabed preparation, and offshore heavy-lift.
- Fleet: Jack-ups, heavy-lift vessels, cable-lay ships, and dredging support assets.
With its modern fleet and record orderbook, DEME has proven itself as one of the fastest-growing names among the largest offshore construction companies.
DEME is one of the fewest companies which is continuously investing in new vessels and updating their fleet with DEME owned vessels, not chartered.
Choosing Among the Largest Offshore Construction Companies
From an insider’s point of view, choosing between the largest offshore construction companies depends on project needs:
- For integrated EPC + subsea projects: Saipem7 leads.
- For subsea production systems: TechnipFMC dominates.
- For heavy-lift and pipelay: Allseas is unrivaled.
- For seabed works and offshore wind: Boskalis is unmatched.
- For renewables expansion and integrated offshore energy: DEME is the rising force.
The Global Impact of the Largest Offshore Construction Companies
The largest offshore construction companies aren’t just big in size; they are vital to global energy security and the energy transition. Without them, deepwater oil & gas wouldn’t flow and offshore wind farms wouldn’t stand.
At this time, the top 5 – Saipem7, TechnipFMC, Allseas, Boskalis, and DEME – represent the cutting edge of engineering, logistics, and project execution. Their fleets, backlogs, and technical expertise guarantee that they’ll remain essential players in shaping the future of offshore energy.
Do you have your own top for the largest offshore construction companies? Let me know, I would be glad to hear from you! What is the best company in this area to work for?