Dark Transits: The Shadow Fleet Keeping Oil Moving

The dashboards say the strait is shut. AIS — the transponder system that broadcasts a ship's identity and position — shows only a handful of crossings a day. Yet crude keeps arriving at refineries from the Gulf. The gap between the visible and the actual is where the shadow fleet operates.

Going dark

The core tactic is simple: switch off the transponder, or spoof it. Over the last 30 days, at least 20 non-Iranian tankers of 250 metres or longer went dark in the Gulf of Oman for between two and 15 days at a time. Track them by satellite instead, and the picture changes: those vessels moved roughly 32 million barrels of crude — about 2.5 million barrels a day — entirely off the AIS map.

Spoofing and staging

Some ships broadcast fake coordinates, appearing to sit calmly off one coast while actually transiting elsewhere. Investigators recently flagged six vessels broadcasting false locations in the Gulf of Oman, alongside 19 acting as blockade runners inside the Gulf. Others simply wait — staging offshore until a window opens, then dashing through.

A near-zero AIS count does not mean near-zero oil. It means the oil that is moving does not want to be seen.

The empty terminals

The contradiction is visible on land, too. On 13–14 June, the crude berths at Iran's main export hub, Kharg Island, sat empty, with about 23 tankers waiting offshore. Yet Vortexa data showed weekly oil arrivals from terminals west of Hormuz — excluding Iran — reaching 3.4 million barrels a day for the week ending 13 June. The trade has not stopped; it has gone quiet, and rerouted.

Who is moving it

Beyond the commercial shadow fleet, even militaries appear to be involved. On 16 June, Reuters reported that US forces were conducting covert ship-to-ship oil transfers inside the Gulf of Oman. Eight separate shipments of Iranian goods bound for foreign buyers were detected in the same period — a reminder that, blockade or not, the economics of oil find a way through.