A laden supertanker burned off the UAE coast on 9 October. The UAE did not confirm oil on its beaches until 23 October, and it still has not named the ship.
We pulled every Sentinel-1 radar pass since the strike. None before 21 October had enough wind to show oil; the 21 October pass shows a slick 35 km long. This week: how to read free radar for oil, and why a calm sea can hide a leak.
| 9 Oct | Gem No.2 struck 13 nm west of Al Jazeera | Record |
| 19 Oct | Fuel smell reported in Sharjah | Record |
| 20 Oct | Windward flags a tanker leaking 25 km out | Record |
| 21 Oct | Slick about 180 sq km (AFP); ministry finds "no indications of concern" | Ministry |
| 21 Oct | Radar shows a 35 km slick offshore | Record |
| 23 Oct | Ministry confirms a tanker spill | Ministry |
| 24 Oct | Slick about 750 sq km; more beaches shut | Record |
14days strike to official confirmation | 11days from the strike to the first public flag | 35km slick length on 21 October |
A tanker struck on 9 October was leaking off Umm Al Quwain by 20 October
Sentinel-1D, 21 October, 02:14 UTC, off Umm Al Quwain. Copernicus Sentinel data 2026, processed by Signal & Shadow
In the early hours of Friday 23 October, the UAE's Ministry of Climate Change and Environment said it had detected a tanker oil spill affecting Umm Al Quwain's beaches and closed every beach and coastal area in the emirate. Sharjah shut Al Hamriyah Beach that afternoon, and on 24 October Ras Al Khaimah closed all of its beaches. On 28 October Sharjah closed all of its beaches too. The ministry has not named the tanker or said what caused the spill. Martin Kelly of Orbital Risk Intelligence told Reuters it came from a tanker called the Gem No.2.
None of this started on 23 October: on 9 October UKMTO reported a vessel struck by an unknown projectile 13 nautical miles west of Al Jazeera, with a fire that was later extinguished. Vanguard and two shipping and security sources named it as the Gem No.2, a fully laden crude supertanker last seen in LSEG tracking data at anchor off the coast. On 10 October India's shipping minister said all 22 Indian seafarers were safe after a drone attack on a Panama-flagged tanker at Sharjah Anchorage.
So when did the open record hold enough to flag the leak? For the risk, by 10 October: a laden tanker, a confirmed strike and fire, and a fixed anchorage off a coast where desalination plants are crucial for the water supply. For the leak itself, by Tuesday 20 October, when Windward posted on X that a VLCC-sized vessel was leaking about 25 km offshore. That was three days before the ministry spoke, and residents had been reporting the smell since 19 October.
This will not be the last one: Washington Institute data makes October the worst month for attacks on commercial shipping in the Strait of Hormuz and nearby waterways. Wim Zwijnenburg of PAX, citing imagery from 26 October, said the slicks were "a few hundred metres away from the intake of the Naqaa desalination plant".
Open Copernicus Browser, choose Sentinel-1 and centre on the anchorage between Al Jazeera Al Hamra and Umm Al Quwain. Log every pass from 9 October with its scene ID and UTC time, screenshot each with the date visible and hash the exports. Note the modelled wind for each pass: below about 3 m/s a pass can neither show nor rule out oil.