The Ohio class of nuclear-powered submarines includes the United States Navy's 14 ballistic missile submarines (SSBNs) and its four cruise missile submarines (SSGNs). Each displacing 18,750 tons submerged, the Ohio-class boats are the largest submarines ever built for the U.S. Navy. They are also the third-largest submarines ever built, behind the Russian Navy's Soviet era 48,000-ton Typhoon class, the last of which was retired in 2023, and 24,000-ton Borei class. Capable of carrying 24 Trident II missiles apiece, the Ohio class are equipped with just as many missiles as, if not more than, either the Borei class (16) or the deactivated Typhoon class (20).
USS Ohio, during her commissioning ceremony in 1981.
USS Michigan (SSBN-727) at a dry-dock in November 2002, before its conversion to an SSGN
USS Ohio being converted from an SSBN to an SSGN in March 2004
Artist's concept of an Ohio-class SSGN launching Tomahawk Land Attack Missiles
A nuclear submarine is a submarine powered by a nuclear reactor, but not necessarily nuclear-armed. Nuclear submarines have considerable performance advantages over "conventional" submarines. Nuclear propulsion, being completely independent of air, frees the submarine from the need to surface frequently, as is necessary for conventional submarines. The large amount of power generated by a nuclear reactor allows nuclear submarines to operate at high speed for long periods, and the long interval between refuelings grants a range virtually unlimited, making the only limits on voyage times being imposed by such factors as the need to restock food or other consumables.
British Astute-class submarine
USS Nautilus, the first nuclear-powered submarine.
The smallest nuclear-powered submarine, the U.S. Navy's NR-1.
The nuclear-powered VMF Typhoon-class submarines were the world's largest-displacement submarines.