Soviet submarine K-278 Komsomolets

The K-278 Komsomolets was the Project-685 Plavnik (Russian: проект-685 плавник, meaning "fin", also known by her NATO reporting name of "Mike"-class), nuclear-powered attack submarine of the Soviet Navy; the only submarine of her design class.

In the inventory of the Soviet military, K-278 was unique for her submarine depth rating, having reached a depth of 1,020 metres (3,350 feet) in the Norwegian Sea on 4 August 1984. Although K-278 was commissioned in the Soviet Navy to evaluate the technology for the fourth-generation of Russian nuclear submarines, she was capable of combat maneuvering and deployment. During her third operational patrol in the Arctic Ocean in 1989, a serious fire in the aft compartments led to her sinking in the Barents Sea off the coast of Norway.

Despite the fire in the engineering compartment, K-278 was able to surface and remained afloat for approximately five hours before sinking. Many of the crew perished before rescue, leading to 42 total dead (and 27 survivors).

The wrecked submarine is on the floor of the Barents Sea, about 1.7 km (1 mile) deep, with her nuclear reactor and two nuclear warhead-armed torpedoes still on board.

The Project 685 was designed by the Rubin Design Bureau in response to a challenge to develop an advanced submarine that could carry a mix of torpedoes and cruise missiles with conventional or nuclear warheads. The order to design the submarine was issued in 1966 and design was completed in 1974. The keel was laid down on 22 April 1978 at Severodvinsk. K-278 was launched on 3 June 1983 and commissioned on 28 December 1983.

K-278 had a double hull, the inner one being composed of titanium, which gave her an operating depth far greater than that of the best American submarines. The pressure hull was composed of seven compartments with the second and third protected by stronger forward and aft bulkheads creating a "safety zone" in case of an emergency. An escape capsule was fitted in the fin above these compartments to enable the crew to abandon ship in the event of an underwater emergency. Initial Western intelligence estimates of K-278's speed were based on the assumption that the boat was powered by a pair of liquid metal cooled reactors. When the Soviet Union revealed that the submarine used a single OK-650b-3 conventional pressurized-water reactor, these speed estimates were lowered.

According to Norman Polmar and Kenneth J. Moore, two Western experts on Soviet submarine design and operations, the Project 685's advanced design included many automated systems which allowed for fewer crew members than usual for a submarine of her size. The manning table approved by the Soviet Ministry of Defense in 1982 called for a crew of 57 men. This was later increased to 64: 30 officers, 22 warrant officers, and 12 petty officers and seamen. At the time of the boat's sinking, 69 were aboard.

In October 1988, K-278 became one of the few Soviet submarines to be given a name: Komsomolets (Комсомолец, meaning "a member of the Komsomol"), and her commanding officer, Captain 1st rank Yuriy Zelenskiy was honoured for diving to 1,020 metres (3,350 ft).