Rowers near the Caddebostan shore of Turkey’s Marmara Sea cut through a layer of marine mucilage, a green-grey sludge that develops on the water’s surface owing to the proliferation of microorganisms. The substance, informally dubbed sea snot, was first documented in Turkish waters in 2007. Researchers warn that the mucilage is harmful to sea life and is likely to occur more often in future because of climate change