The Sikorsky SH-3 Sea King (company designation S-61) is an American twin-engined anti-submarine warfare (ASW) helicopter designed and built by Sikorsky Aircraft. A landmark design, it was the world's first amphibious helicopter and one of the first ASW rotorcraft to use turboshaft engines.
Introduced in 1961, it served in the United States Navy as a key ASW and utility asset for several decades before being replaced by the non-amphibious Sikorsky SH-60 Seahawk in the 1990s. The type also proved popular in civil service and with foreign military customers. As of 2015, many remain in service in nations around the world. The Sea King has been built under license by Agusta in Italy, Mitsubishi in Japan, and by Westland in the United Kingdom as the Westland Sea King. The major civil versions are the S-61L and S-61N.