After gunnery and torpedo practice off the west coast of the United States, she participated in Fleet Problem XVIII in the Hawaiian area, April–May 1937, and toward the end of the year underwent extensive overhaul at Mare Island Navy Yard.

At the outbreak of the war with Japan with the japanese attack on Pearl Harbor on 7 December 1941, Porpoise, commanded by Joseph A. Callaghan, was at Olongapo in the Philippine Islands, undergoing a refit.

Conducting her second war patrol in the Netherlands East Indies from 9 February to 30 March 1942, Porpoise scored on a cargo ship before anchoring at Fremantle, Western Australia.

After a major overhaul at Mare Island, Porpoise departed Pearl Harbor for her fourth war patrol - from 30 November 1942 to 15 January 1943 - off the coast of Honshū, Japan.

During her voyage, an Allied tanker mistakenly opened gunfire on her in the Pacific Ocean on 13 August 1943, but Porpoise maneuvered away southward on the surface and sustained no damage.