B-427 was a Project 641 () diesel-electric attack submarine of the Soviet Navy. The "B" (actually "Б") in her designation stands for большая (bolshaya, "large"). Commissioned in 1971, the submarine operated with the Russian Pacific Fleet until decommissioning in 1994. The boat was sold to a group of Australian businessmen, who converted her into a museum vessel, which was placed on display at the Australian National Maritime Museum (under the name Foxtrot-540) from 1995 until 1998, then at Long Beach, California (under the name Podvodnaya Lodka B-427 Scorpion) in 1998. The submarine is still on display as of 2013.