Is the shadow fleet the same as the dark fleet?

Yes. IMO resolution A.1192(33) uses the two terms interchangeably. “Dark” refers to ships going dark by switching off their AIS.

How many ships are in the shadow fleet?

There is no official count, because the term describes behaviour, not a register. What can be counted are ships designated on sanctions lists; the live table on this page shows those counts for the lists Seadar reads.

Is it illegal for a ship to switch off AIS?

Ships required to carry AIS must keep it on, except when the master judges that transmitting would compromise the ship’s safety or security. Switching it off to avoid detection is listed by the IMO as a sign of dark fleet operations.

What is the shadow fleet (dark fleet)?

Updated Sep 28, 2026 · 3 min read

In short

The “shadow fleet” or “dark fleet” is the IMO’s term for ships engaged in illegal operations to circumvent sanctions, evade safety or environmental rules, avoid insurance costs or carry out other illegal activities. The IMO Assembly defined it in resolution A.1192(33) of December 2023, listing warning signs such as switching off AIS, concealing a ship’s identity, avoiding inspections and lacking proper insurance. Governments respond by designating individual ships on sanctions lists; Seadar shows those designations, with their source, on each ship’s page.

The IMO definition

Resolution A.1192(33) decides that “dark fleet” or “shadow fleet” mean ships “engaged in illegal operations for the purposes of circumventing sanctions, evading compliance with safety or environmental regulations, avoiding insurance costs or engaging in other illegal activities”, which may include:

carrying out unsafe operations that do not follow international regulations and industry standards;
intentionally avoiding flag state and port state control inspections;
not maintaining adequate liability insurance or other financial security;
intentionally avoiding commercial screenings or inspections;
not operating under a transparent corporate governance policy;
intentionally taking measures to avoid detection, such as switching off AIS or LRIT transmissions or concealing the ship’s actual identity, without a legitimate safety or security reason.

The resolution notes with grave concern the risk of incidents, especially during ship-to-ship (STS) transfers of cargo at sea, which can disguise where a cargo came from or is going.

The warning signs, and their limits

AIS gaps and switch-offs. A ship that stops transmitting in a sensitive area and reappears later. But the IMO itself notes that non-receipt of AIS “may not be determinative of illegal activity but may warrant further investigation”: most gaps are simply areas without receivers. See how ship tracking works.
Identity games. Frequent renaming and reflagging, flags of registries that do not exist or have not authorised the ship, or a transmitted IMO number that belongs to another ship.
Age and opacity. Older tankers bought through newly formed companies with unclear ownership, and insurance from unknown providers.
Ship-to-ship transfers in open water rather than in ports or established transfer areas.

None of these proves anything on its own. Plenty of legitimate ships are old, change flags or transfer cargo at sea. That is why Seadar never labels a ship “shadow fleet”: it shows what governments have designated and what the ship has observably done, each with its source.

Sanctions lists that name ships

Several governments designate individual ships by IMO number, which bars their own nationals and companies from dealing with them and, in some cases, from letting them into port. Seadar reads these lists and links every designated ship to its vessel page: the US Treasury’s OFAC SDN list, the EU’s list of designated vessels, the UK Sanctions List, Canada’s autonomous sanctions list and New Zealand’s Russia sanctions register. Each list page shows every designated ship with its designation, its last AIS position and the port calls Seadar has detected since.

Ships on sanctions lists, as Seadar tracks them

Live from Seadar

Current vessel designations on the lists Seadar reads, straight from each list.

List	Ships designated
OFAC SDN list (US)	1,539
UK Sanctions List	663
Canadian autonomous sanctions list	736
EU designated vessels (Official Journal)	730
New Zealand Russia Sanctions Register (MFAT)	210

1,637 distinct ships are currently designated on at least one of these lists. 266 of them were heard on AIS by Seadar in the last 7 days.

Designations are the lists’ own facts. The distinct-ship count and the “heard in the last 7 days” count are Seadar’s, from its AIS reception; a ship Seadar did not hear may simply be out of its coverage. As of Oct 1, 2026, 13:17 UTC

How to check a ship

Look the ship up by IMO number, not by name: names change and are reused.
On its Seadar page, the sanctions section lists every current designation with the list, programme and date, and links to the official source to verify it.
The identity history shows the flags, names and MMSIs the ship has used, from AIS.
The track and port calls show where Seadar has actually heard it.

A match on Seadar is a starting point for due diligence, not a legal determination. Always confirm a designation against the official list before acting on it.

Questions and answers

Is the shadow fleet the same as the dark fleet?: Yes. IMO resolution A.1192(33) uses the two terms interchangeably. “Dark” refers to ships going dark by switching off their AIS.
How many ships are in the shadow fleet?: There is no official count, because the term describes behaviour, not a register. What can be counted are ships designated on sanctions lists; the live table on this page shows those counts for the lists Seadar reads.
Is it illegal for a ship to switch off AIS?: Ships required to carry AIS must keep it on, except when the master judges that transmitting would compromise the ship’s safety or security. Switching it off to avoid detection is listed by the IMO as a sign of dark fleet operations.

Look up a ship

Search any vessel by name, IMO number or MMSI for its free Seadar profile: live position, identity history, ownership, inspections and sanctions.

Sources

Primary sources for the facts in this guide. Figures labelled as Seadar data come from Seadar’s own records, with their method stated next to them.

Published Sep 28, 2026 · For information only. Not for navigation, and not a substitute for the official sources cited.