THRESHER

first of a class of U.S. nuclear-powered attack submarines, launched in 1960. During sea trials after commissioning it sank with 129 persons on board in April 1963, about 200 miles (300 km) off the New England coast. The cause of the tragedy, considered the worst in submarine history, was never determined. In August 1963, wreckage of the vessel was spotted by the bathyscaphe Trieste at a depth of about 8,500 feet (2,600 m). Thresher, launched July 9, 1960, displaced 3,750 tons and was 279 feet (about 85 m) long. It was armed with Subroc antisubmarine missiles that could be fitted with either high explosives or a nuclear warhead. Thirteen other submarines of the Thresher class were launched between 1961 and 1966.