Ship Suspected of 150-Mile-Long Oil Slick in Red Sea

An approximately 150-mile-long oil slick that has been spotted in the Red Sea is believed to have been released by a merchant ship, according to satellite-monitoring environmental group SkyTruth.

The discharge was initially spotted off the coast of Sudan by Sentinel-2 satellite imagery on May 19, 2023.

SkyTruth reports that the slick measures about 250km in length and was probably discharged from a moving vessel over the course of several hours. The company said the volume of the spill equates to at least 120,000 gallons, but is likely to be much more depending on the thickness of the oil on the surface.

“The unusually large size and volume of this slick suggests it could be the result of tank washing by a petrochemical tanker, rather than bilge discharge from a cargo ship,” SkyTruth said a Twitter thread of its findings thus far.

The company used AIS data to narrow down possible culprits. It identified three ships, a Vietnamese-flagged tanker, a Panama-flagged containership, a Marshall Islands-flagged bulk carrier, and a Bahamas-flagged bulk carrier, as suspects.

SkyTruth added that its analysis assumes the polluting vessel was not “running dark,” meaning it was broadcasting AIS at the time of the release, but could not rule out that a separate “dark” vessel was responsible.

Oil discharges from ships are regulated under the IMO’s International Convention for the Prevention of Pollution from Ships (MARPOL), specifically MARPOL Annex I which addresses oil pollution prevention.