The Typhoon class submarine is a type of nuclear-powered ballistic missile submarine deployed by the Soviet Navy in the 1980s. With a maximum displacement of 48,000 tonnes, Typhoons are the largest class of submarine ever built. Typhoon submarines are among the quietest sea vessels in operation, being quieter and yet more maneuverable than their predecessors. This is partly due to the vessels' large size, which allows them to minimize noise caused by water. A Typhoon class submarine can stay submerged for periods up to 180 days in normal conditions, and potentially more if necessity arises.