Up to 15,000 metric tonnes of heavy fuel oil spilled into the Mediterranean when Lebanon's Jiyyeh power plant was bombed in mid-July by the Israeli military.
The oil slick drifted north for 150km. The clean-up operation only began a month after the bombing, when the conflict ended.
This picture from October 17 shows oily water at the small port of Dalieh, in West Beirut.
Picture by Wael Hmaidan.