What Sea1 Offshore does

Sea1 Offshore is a Norwegian offshore support vessel (OSV) operator publicly listed on the Oslo Stock Exchange under ticker SEA1 (formerly Siem Offshore, rebranded in May 2024). The company operates a fleet of 23 specialized vessels spanning anchor handling tug supply (AHTS), platform supply vessels (PSV), subsea construction, well intervention, offshore wind service, scientific drilling, oil spill response (OSRV), and fast crew vessels (FCV). Headquartered in Kristiansund, Norway, with operational offices in the United Kingdom, Australia, Brazil, and Canada, Sea1 serves major international energy and offshore-wind clients including Helix Energy Solutions and Equinor under long-term contracts.

The business model centers on time-charter and contract-based vessel hire to oil and gas majors and offshore wind developers, with $701 million in firm backlog and $569 million in options providing multi-year revenue visibility. Revenue is generated through day-rate contracts and project-based engagements, with durations ranging from spot and short-term extensions to multi-year firm commitments (3-5 years). The fleet is class-compliant with DNV standards and increasingly incorporates emissions-reduction technologies, including a new order for four methanol-ready offshore energy support vessels (OESVs) at Cosco Shipping with deliveries from 2027, supported by a $315 million credit facility.

In Q4 2025, the company reported a 312% year-over-year increase in net profit to $14.4 million, alongside an EBITDA margin of 52%. Net interest-bearing debt was reduced 23% to $208.5 million and cash position grew 26.5% to $86.4 million, with a book equity ratio of 54%. Annual revenue for 2025 was $272 million, down from roughly $340 million in 2024, reflecting the deliberate divestment of older lower-margin vessels to related parties and the transfer of 11 vessels to Aurora Offshore as part of a fleet renewal strategy.

Name

Sea1 Offshore

Legal name

SEA1 Offshore Inc.

Website

https://sea1offshore.com

Company type

Public

Founded year

2005

Operating status

Operating

Headcount range

1,001–5,000 employees

Short description

Sea1 Offshore is a Norwegian offshore support vessel operator (OSLO: SEA1) running a 23-vessel fleet of AHTS, PSV, subsea, well intervention, and offshore wind service vessels under multi-year contracts with major energy and renewables clients.

Ownership category

akta.pro rank

Product category

Offshore Support Vessel Services

NAICS

Other Support Activities for Water Transportation (48839), Support Activities for Water Transportation (4883)

SIC

Water Transportation (4400), Oil & Gas Field Services, Nec (1389)

akta.pro primary industry

Offshore Support & Marine Logistics Vessel Operators (PSV/AHTS) (TLADABAL)

akta.pro secondary industry

Offshore Marine & Aviation Support (PSVs, AHTS, Crew Boats, Helicopters) (EUALABAJ)

Keywords

• Offshore support vessels
• Marine transportation services
• Vessel time chartering
• Subsea construction vessels
• Offshore wind services

Headquarters

HQ city

Kristiansund

HQ country

Norway

HQ region

Europe

Offices6 records

Markets served

GTM type

B2B

Offering type

Services

Cost components

Personnel, Operations, Supply Chain, Infrastructure, Technology or R&D, Marketing or Sales

Revenue model

1. Vessel Time Charters: Revenue generated from time charter contracts for the company's fleet of 23 offshore support vessels, including day rates for AHTS, PSV, subsea, well intervention, and other vessel types. Contracts range from short-term spot market engagements to multi-year firm commitments.

Pricing tiers

Go-to-market motion1 record

Distribution channels4 records

Marketing channels8 records

Core offering

Sea1 Offshore operates and manages a global fleet of 23 offshore support vessels — including Anchor Handling Tug Supply (AHTS), Platform Supply (PSV), Subsea Construction, Well Intervention, Renewables, Scientific Drilling, Oil Spill Recovery (OSRV), and Fast Crew (FCV) vessels — delivered via time charter contracts to oil & gas operators, offshore wind developers, and research institutions worldwide. The company also services hybrid battery, LNG, and methanol-ready vessel technologies to reduce environmental footprint, with multi-year contract backlog providing revenue visibility.

Product overview

Sea1 Offshore (formerly Siem Offshore) operates as a global offshore vessel provider offering a diversified fleet of 23 offshore support vessels. The fleet comprises multiple vessel types including Platform Supply Vessels (PSV), Anchor Handling Tug Supply Vessels (AHTS), Subsea/Offshore Subsea Construction Vessels (OSCV), Well Intervention Vessels (WIV), Renewables Vessels, Scientific Drilling Vessels, Oil Spill Recovery Vessels (OSRV), and Fast Crew Vessels (FCV). The company also has new vessel orders for methanol-ready Offshore Energy Support Vessels (OESV) based on the ST-245 design, scheduled for delivery from 2027. Services are offered across oil & gas, renewables, and research sectors, providing vessel chartering, subsea operations, well intervention, and scientific support worldwide.

Differentiator

Problem solved

Functional benefit

Products and services

• Platform Supply Vessels (PSV) Vessels designed to transport supplies, equipment, and cargo to offshore oil and gas platforms, supporting drilling and production operations.
• Anchor Handling Tug Supply (AHTS) Multi-purpose vessels equipped for anchor handling, towage, and supply operations for offshore installations.
• Subsea / Offshore Subsea Construction Vessels (OSCV) Vessels equipped for subsea construction, ROV support, and underwater intervention operations including offshore wind farm installation and maintenance.
• Well Intervention Vessels (WIV) Specialized vessels for well intervention operations, workover services, and well completion support.
• Renewables Vessels Vessels supporting offshore renewable energy operations including wind farm installation, maintenance, and construction support.
• Scientific Drilling Vessels Vessels equipped for scientific research drilling operations, including the JOIDES Resolution for research expeditions.
• Oil Spill Recovery Vessels (OSRV) Specialized vessels designed for oil spill response, containment, and recovery operations.
• Fast Crew Vessels (FCV)

Quantifiable outcome

• Q4 2025 net profit surged 312% to $14.4 million from $3.5 million in Q4 2024
• +5 more outcomes

Named customers7 records

Segments3 records

Ideal customer profiles3 records

Technology focussed No

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Feature6 records

Partnerships

Five partnerships are on record, tiered minor and core.

• Aurora OffshoreminorChannel Partner/ Reseller/ Distributor · 1 January 2025Norway-based Aurora Offshore took management of two AHTS vessels (Siem Pearl and Siem Challenger) from Sea1 Offshore. This is the first two of 11 vessels set to transfer under a new collaboration. Vessel transfers completed at Harøy and Aberdeen respectively.
• DeepOceanminorChannel Partner/ Reseller/ DistributorDeepOcean signed an agreement with Boskalis to charter the subsea vessel Boka Spearfish, a vessel previously operated by Sea1 Offshore. The vessel will be equipped with ROVs and mission-critical systems, strengthening DeepOcean's fleet.
• Cosco ShippingcoreStrategic or Co-development PartnerCosco Shipping is building four methanol-ready Offshore Energy Support Vessels (OESVs) for Sea1 Offshore, based on the ST-245 design. Vessel deliveries are scheduled from 2027 through the first half of 2028. This represents a major new-build investment financed by a $315 million credit facility.
• Helix Energy Solutions GroupcoreStrategic or Co-development PartnerSea1 Offshore and Helix Energy Solutions entered into agreements for Well Intervention Vessels Siem Helix 1 (3-year firm) and Siem Helix 2 (5-year firm) with subsequent options, replacing existing contracts. Commencement in Q1 2022. Total contract backlog for SIOFF reached USD 440 million following this agreement.
• Christian Radich FoundationminorStrategic or Co-development PartnerSea1 Offshore teams up with the Christian Radich Foundation on a new education program, supporting maritime education and training.

Scale indicators10 records

Recent moves15 records

Expansion highlights6 records

Direct peers

• Bourbon Offshore: Global OSV operator headquartered in France with a deep fleet of AHTS and PSVs serving deepwater oil and gas markets worldwide. Comparable through vessel type mix, international chartering model, and exposure to both oil and gas and emerging offshore wind markets.
• Edison Chouest Offshore: Privately held US-based operator of OSVs, platform supply vessels, and crew boats serving global offshore markets. Directly comparable in vessel chartering model and customer base (oil majors, renewables developers), with a similarly diversified geographic footprint.
• Solstad Offshore: Norwegian-based OSV operator with a large global fleet of AHTS, PSV, and subsea construction vessels serving oil and gas and renewables clients. Directly comparable in vessel mix, geographic footprint, and North Sea customer base, and is a key Norwegian-headquartered competitor to Sea1.
• Vroon Offshore: Netherlands-based operator of PSVs, AHTS, and subsea support vessels serving the offshore energy sector in the North Sea and globally. Comparable in fleet composition, European customer relationships, and renewables exposure.
• DOF (DOF Subsea / DOF Group): Norwegian OSV and subsea services operator with an AHTS/PSV/subsea fleet comparable in scale to Sea1. Both compete for the same North Sea, Brazil, and Asia-Pacific contracts, and DOF has similarly undergone restructuring with renewed charter awards.
• Havila Shipping: Norwegian public OSV company operating AHTS and PSV vessels in the North Sea and Mediterranean. Comparable scale and business model, with overlapping tendering against Norwegian operators including Sea1.

Emerging players

• DeepOcean: Norwegian-based subsea services provider operating ROV and subsea construction vessels, and a former Sea1 chartering partner. Comparable through subsea vessel operations and offshore wind construction exposure, though focused more narrowly on subsea intervention than full-spectrum OSV.
• Aurora Offshore: Norwegian OSV management company that has assumed management of 11 AHTS vessels from Sea1. Comparable in vessel type focus (anchor handling) and North Sea customer base, and represents both a partnership and emerging fleet management competitor.

Broad incumbents

• Tidewater Inc. One of the largest global OSV operators with over 200 vessels covering PSV, AHTS, crew boats, and specialty vessels. Significantly larger than Sea1 but competes for the same global tenders and operates a similar chartering model.
• Maersk Supply Service: Danish-headquartered OSV operator (part of A.P. Moller-Maersk) with a global fleet including AHTS, PSV, and subsea vessels. Comparable in vessel categories and offshore energy customer base, though backed by a much larger parent group.

Market position

Strengths5 records

Weaknesses5 records

Competitive moat5 records

Key risks7 records

Key highlights7 records

Customer concentration

• Facebookfacebook.com/siemoffshoreinc
• LinkedInlinkedin.com/company/siem-offshore-as
• Instagraminstagram.com/siemoffshore/?hl=nb

Revenue estimate

Valuation estimate

Number of profiles

Profiles15 records

Subsidiaries1 record

Funding overview

Funding rounds

Investors

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A1 record

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about Sea1 Offshore