The Mark 35 torpedo was the first of the United States Navy deep-diving anti-submarine torpedoes designed for surface launch. This electrically propelled 21-inch (53-cm) torpedo was 162 inches (4.11 m) long, weighed 1770 lb (803 kg), and carried a 270 lb (122.5 kg) Torpex high explosive warhead. This torpedo used one of the earliest active guidance systems and was introduced in 1949, but was classified as obsolete in the 1960s.