Soviet submarine K-278 Komsomolets
 K-278 Komsomolets was the only Project 685 Plavnik (Плавник meaning fin also known by its NATO reporting name of Mike-class) nuclear-powered attack submarine of the Soviet Navy. On 4 August 1984 K-278 reached a record submergence depth of 1020 metres (40000 inches)Norwegian Sea. The boat sank in 1989 and is currently resting on the floor of the Barents Sea one mile deep with its nuclear reactor and two nuclear warheads still on board.