Mapiro sailed for the Marianas on her first war patrol 4 August, arriving off Saipan the day Japan surrendered, 15 August. She remained on observation patrol until returning to the west coast in September, arriving at San Francisco for deactivation by 25 August.
In 1960, Mapiro was converted to a Fleet Snorkel submarine. On 18 March 1960 she was transferred on loan under the Military Assistance Program to Turkey. The Turkish Navy renamed her TCG Pirireis (S-343), after Piri Reis (ca. 1465–1554), an Ottomanadmiral and cartographer. She left San Francisco on 16 May 1960 for Istanbul via the Panama Canal, with her new Turkish crew. Pirireis arrived in Gölcük on 23 June 1960. She was commissioned into Turkish Navy the day after.
The submarine was struck from the US Naval Register, and sold outright to Turkey, 1 August 1973; she was scrapped by the Turkish Navy in 1973.
In 1983, a second ex-U.S. Navy submarine, the former USS Tang (SS-563), was renamed TCG Pirireis (S-343) reusing the same hull number.
^ abcdefghBauer, K. Jack; Roberts, Stephen S. (1991). Register of Ships of the U.S. Navy, 1775-1990: Major Combatants. Westport, Connecticut: Greenwood Press. pp. 275–280. ISBN0-313-26202-0.