USS Sennet (SS-408) was a Balao-class submarine, a ship of the United States Navy named for the sennet, a barracuda. Sennet was laid down on 8 March 1944 by the Portsmouth Navy Yard in Kittery, Maine, launched on 6 June 1944, sponsored by Mrs. Roscoe W. Downs, and commissioned on 22 August 1944. Sennet was fitted out by 18 September. She held training exercises and torpedo-tube testing off the coast of Connecticut and Rhode Island until 22 October. The submarine then tested mines and torpedoes for the Mine Warfare Test Station, Solomons Island, Md. On 11 November, Sennet proceeded to the operations area off Balboa, C. Z. and conducted further training exercises. The submarine departed Balboa on 29 November for Pearl Harbor and arrived there on 16 December 1944. Sennet'''s topside armament was increased to two guns, two 40 millimeter guns, and three .50 caliber machine guns before departing Pearl Harbor for her first war patrol on 5 January 1945. First and second patrols, January–March 1945 Sennet patrolled north of the Bonin Islands until 28 January. She made two attacks on a large tanker with three escorts on 21 January but scored no hits. The following week, the submarine sank one 500-ton picket boat and damaged another.Sennet refitted at Saipan from 31 January to 7 February, when she began her second war patrol off southern Honshū, Japan. On 13 February, two 300-ton picket boats were sunk by the combined gunfire of Sennet, , and . Three days later, the submarine attacked enemy minelayer the Nariu with an offset spread of torpedoes from her stern tubes, then went deep to . Two torpedoes were heard to explode. While going deep, Sennet was rocked hard by two aircraft bombs which exploded beneath her. The submarine surfaced an hour later and saw a large oil slick and approximately 40 Japanese clinging to debris but no trace of the Nariu which had sunk. Third and fourth patrols, April–August 1945 Sennet was refitted by in Apra Harbor, Guam, 9 March – 2 April. Patrolling off Honshū again from 3 April to 16 May, she was twice straddled by torpedoes fired from patrol boats while she was surfaced off Miki Saki on 16 April. Three days later, the submarine torpedoed and sank the cargo ship Hagane Maru. On 22 April, Sennet attempted to save a P-51 pilot who had bailed out near her but the man