She cruised twice to Hawaiian waters and once to the Panama Canal Zone to participate in large-scale fleet exercises. "Cachalot" cleared San Diego on 16 June 1937, bound for New London, Connecticut, and duty in experimental torpedo firing for the Newport Torpedo Station and sonar training for the New London Submarine School until 26 October 1937, when she began a lengthy overhaul at the New York Navy Yard. This included replacement of her troublesome engines with General Motors Winton engines. A year later, she sailed for participation in a fleet problem, torpedo practice and sound training in the Caribbean Sea and off the Canal Zone, and on 16 June 1939 reported at Pearl Harbor for duty with the Submarine Force and the Scouting Force. War came to "Cachalot" as she lay in Pearl Harbor Navy Yard in overhaul. In the Japanese attack on Pearl Harbor of 7 December 1941, one of her men was wounded, but the submarine suffered no damage. Yard work on her was completed at a furious pace, and on 12 January 1942 she sailed on her first war patrol. After fueling at Midway Island, she conducted a reconnaissance of Wake Island, Eniwetok, Ponape, Truk, Namonuito, and the Hall Islands, returning to Pearl Harbor on 18 March with vitally needed intelligence of Japanese bases. Her second war patrol, for which she cleared from Midway on 9 June, was conducted off the Japanese home islands, where she damaged an enemy tanker. Returning to Pearl Harbor on 26 July, she cleared on her final war patrol on 23 September, penetrating the frigid waters of the Bering Sea in support of the Aleutian Islands operations. Over-age and lacking endurance for strenuous war patrols, "Cachalot" still had a key role to play, acting as training ship for the Submarine School at New London. She served there from late 1942 until 30 June 1945, when she sailed to Philadelphia, Pennsylvania, being decommissioned there on 17 October. She was sold for scrap on 26 January 1947.