A thick layer of slime, known as marine mucilage or "sea snot" is seen covering the beach of the Marmara Sea in Kocaeli, Turkey, June 11, 2021. /CFP

Reportedly, the mucilage develops as a result of untreated waste dumped into the sea, climate change and the excessive proliferation of phytoplankton. /CFP

More than 25 sea surface-cleaning and barrier-laying boats have been deployed to clean up and prevent the spread of the mucilage, which threatens marine life and Istanbul's fishing industry. /CFP

Seagulls are seen at a ferry port in front of "sea snot" at a harbor on the Marmara Sea in Istanbul, Turkey, June 11, 2021. /CFP

An aerial view of a man in a paddleboat passing through "sea snot" at a beach on the Marmara Sea shoreline in Kocaeli, Turkey, June 11, 2021. /CFP