Dark Fleet (Shadow Fleet): Maritime Glossary

A dark fleet, also called a shadow fleet, is a group of ships operated to evade sanctions or to avoid the safety, environmental, insurance and inspection rules that apply to normal trading. The term is used most often for older tankers moving sanctioned oil, but the same tactics appear in other trades.

How the IMO describes it

In December 2023 the IMO Assembly adopted a resolution aimed at illegal operations by the dark fleet or shadow fleet. The practices it points to include unsafe operation, deliberately avoiding flag state and port state inspections, sailing without adequate liability insurance, avoiding commercial screening, opaque ownership and governance, and switching off AIS or other tracking without a legitimate safety reason. It also urged flag states to act on ship to ship transfers used to hide cargo.

Warning signs of a dark fleet vessel

Long or repeated AIS gaps, especially near known transfer areas
Frequent changes of name, flag or registered owner
Ownership through single ship companies with no visible operating history
No insurance from a recognised protection and indemnity (P&I) club
Ship to ship transfers in open water rather than at a recognised anchorage
An old vessel with a thin or missing port state control record

Why it matters to buyers and suppliers

Sanctions risk does not stop with the shipowner. The May 2020 advisory from OFAC, the US State Department and the US Coast Guard names ship chandlers, port operators, insurers, brokers and financial institutions among the parties expected to run risk based checks. Supplying stores, spares or bunkers to a listed vessel can expose a company to penalties. The EU, for example, bans listed vessels from its ports and bars EU operators from providing a wide range of maritime services to them; by its 17th package in May 2025 the EU had listed 342 vessels.

Before you quote or deliver, screen the vessel: check the IMO number against sanctions lists, look at ownership and flag history, and review its tracking record.

Old ships are not automatically dark fleet

Age alone does not make a vessel part of the dark fleet. Plenty of older ships trade legally with proper insurance, a clear owner and a full inspection record. What marks a dark fleet vessel is a pattern: several warning signs together, such as hidden ownership, missing insurance, AIS gaps and transfers at sea, rather than any single one.

Tidal screens vessels and counterparties for sanctions, ownership and compliance history, and documents every decision. See maritime sanctions screening software or maritime due diligence.

Sources

AIS gap Ship to ship transfer Bunkering Port call Ship chandler All glossary terms →

Frequently asked questions

What is the dark fleet in shipping?

The dark fleet, or shadow fleet, is a group of ships operated to evade sanctions or to avoid safety, insurance and inspection rules. Typical tactics include switching off AIS, changing names and flags, hiding ownership and moving cargo through ship to ship transfers at sea.

Is the dark fleet the same as the shadow fleet?

Yes. The two terms are used for the same thing. The IMO resolution adopted in December 2023 refers to the dark fleet or shadow fleet together.

How can you tell if a vessel is part of the dark fleet?

Common warning signs are long AIS gaps, frequent name, flag or owner changes, single ship owning companies, no recognised P&I insurance and ship to ship transfers in open water. Screening the IMO number against sanctions lists is the first check.

Can a ship chandler be penalised for supplying a dark fleet vessel?

It can. The May 2020 US sanctions advisory names ship chandlers among the parties expected to screen counterparties, and EU rules bar EU operators from providing many maritime services to listed vessels.

Dark fleet