The term 'Atom Submarine' refers to the Nautilus, the world's first nuclear-powered submarine. Launched in 1954, the Nautilus was the first vessel to travel under the North Pole and was the prototype for all subsequent nuclear submarines. It was powered by a pressurized water reactor, which allowed it to remain submerged for extended periods of time. The Nautilus was decommissioned in 1980 and is now a museum ship in Groton, Connecticut.