She cruised on the west coast with occasional voyages to Pearl Harbor, Alaska, and the Panama Canal Zone for exercises and fleet problems. On 1 December 1937, "Dolphin" departed San Diego for her new homeport, Pearl Harbor, arriving one week later. She continued to operate in fleet problems and training exercises, visiting the West Coast on a cruise from 29 September to 25 October 1940. Located at Pearl Harbor on 7 December 1941, "Dolphin" took the attacking enemy planes under fire, and then left for a patrol in search of Japanese submarines in the Hawaiian Islands.