Which submarine was the first to be powered by a nuclear reactor?

USS Nautilus was the first submarine powered by a nuclear reactor.

The U.S. Navy commissioned Nautilus in 1954 after its launch in 1954 and construction at Electric Boat in Connecticut. Its S2W reactor supplied heat for steam turbines, allowing the submarine to remain submerged for far longer than diesel-electric boats and to travel without regularly surfacing for air.

Nautilus used the nuclear reactor for propulsion rather than carrying nuclear missiles. Its achievement changed submarine design because endurance was no longer governed mainly by battery capacity, fuel consumption, or the need to use diesel engines near the surface.

The name echoed Captain Nemo’s fictional vessel in Jules Verne’s Twenty Thousand Leagues Under the Seas, but the naval submarine was a real engineering milestone. Nautilus later became a museum ship at the Submarine Force Library and Museum in Groton, Connecticut.