What is the shadow fleet?

The short version

“Shadow fleet” describes tankers and other vessels that carry sanctioned cargoes while operating outside the ownership, insurance and classification arrangements that the rest of world shipping uses. It is a description of behaviour, not a legal category. No regulation defines it, no authority publishes a register of it, and no two organisations count it the same way.

That matters more than it sounds. When a news report says the shadow fleet numbers “around 1,400 vessels” and a government list contains a few hundred, both can be right, because they are counting different things.

Where the term came from

The phrase entered general use after 2022, when the G7 price cap on Russian crude created a commercial split: vessels that stayed inside the Western services system and accepted the cap, and vessels that left it. But the underlying practice is much older. Tankers moving Iranian and Venezuelan crude had been using the same techniques for years, and the North Korea sanctions regime documented ship-to-ship transfers and AIS manipulation well before Russia’s full-scale invasion of Ukraine.

The International Maritime Organization eventually adopted the vocabulary itself. In December 2023 the IMO Assembly passed resolution A.1192(33), which urges member states to act against illegal operations “by the ‘dark fleet’ or ‘shadow fleet’”, and identifies the specific practices that concern it: unreported ship-to-ship transfers, disabling or manipulating transponders, and fraudulent registration.

That resolution is worth reading precisely because it is not a sanctions instrument. It frames the problem as one of safety and of the integrity of the flag-state system, which is a different argument from the sanctions one and, in some ways, a more durable one.

Three loose tiers

Analysts generally sort vessels into tiers. The boundaries are conventions, not law.

The cleared fleet is ordinary shipping: mainstream owners, a classification society belonging to the International Association of Classification Societies, protection and indemnity cover from an International Group club, and a trade that stays inside the price cap where relevant.

The grey fleet still touches the regulated system somewhere. It might keep recognised class, or use a mainstream insurer, while its ownership sits behind a chain of single-ship companies and its trade patterns have changed to carry sanctioned oil.

The dark fleet has left the regulated system in most respects: cover from insurers whose ability to pay a major pollution claim is untested, class from societies outside the international association, repeated changes of flag and name, and long gaps in transponder coverage.

Cutting across all three is the category this site actually tracks: vessels an authority has named. A hull can be firmly in the dark fleet and appear on no list. Another can be listed by the European Union alone while trading lawfully everywhere else.

Why the numbers differ

Published estimates in 2026 spanned roughly a thousand to well over fourteen hundred vessels. The spread comes from four decisions each counter has to make.

Which vessels count. Some counts include only crude and product tankers above a size threshold. Others add liquefied gas carriers, general cargo ships moving military-related goods, and the small coastal tankers that feed larger ships offshore. The threshold alone can move a total by hundreds.

What qualifies a vessel. One sanctioned voyage, or a pattern? Carrying Russian crude above the cap, or carrying it at all? Using non-Western insurance, or having no traceable insurance?

What the evidence is. Counts based on designations are reproducible: anyone can check them against the published lists. Counts based on behaviour rest on commercial tracking data and on judgements about what a gap in coverage means. Both are legitimate; only the first can be audited by a reader.

When the count was taken. The population turns over constantly as vessels are listed, delisted, sold, renamed or scrapped.

Our own figures are deliberately the narrow kind. This site counts hulls that appear on the OFAC, UK or EU lists, and says which authority listed each one. Those totals are on the statistics page, and they will always be smaller than a behavioural estimate.

What these vessels have in common

Look across the listed population and the same features recur. The ships are old, often past the age at which mainstream charterers would take them. Ownership sits in single-ship companies, frequently in jurisdictions that publish little. Management changes hands soon after a designation. Flags change more often than a normal trading career requires, and sometimes the register itself turns out not to be a register at all.

None of these features is unlawful on its own. Old ships trade legally; single-ship companies are standard practice; changing flag is routine after a sale. What draws attention is the combination, and its timing relative to a designation.

What it means for a specific ship

The honest answer for any individual hull is narrower than the headline. A vessel is not “in the shadow fleet” in a way that carries legal consequences. It is either listed by a particular authority under a particular instrument, with particular effects, or it is not.

That is why every page on this site answers a smaller question than “is this a shadow-fleet ship?”. It answers: who listed this hull, on what date, under which program, with what stated reason, and what does that instrument actually prohibit. The asset freeze, port ban and services ban explainer sets out the difference between those effects, and how a ship gets sanctioned walks through the process at each authority.