A boat sails across the Sea of Marmara which is covered with sea snot on 12 June, 2021.
Greece is investigating a potential outbreak of “sea snot” in the waters off the island of Lemnos, just weeks after Turkey vowed to clear its seas of the same “scourge”.
Sea snot is thick organic sludge made up of compounds released by marine organisms, which thrives in areas where nutrient-rich sewage flows into the sea.
This organic matter, also known as marine mucilage, can sink below the waves’ surface and can suffocate marine life.
It has recently coated the Sea of Marmara in Turkey, leading officials there to launch an intensive cleaning programme.