Casco was refloated on 12 September 1942, and, after emergency repairs at Dutch Harbor and Kodiak, she received a thorough overhaul at Puget Sound Navy Yard.

Casco returned to duty in the Aleutian Islands in March 1943, operating at Constantine Harbor, Amchitka, as tender to Fleet Air Wing Four (FAW-4).

Casco's service in these waters where weather was often as formidable an enemy as the Japanese ended in November 1943, when she left for overhaul at Puget Sound Navy Yard.

During one of her stays in the Aleutians, an OS2U Kingfisher from the Casco was borrowed by Colonel William O. Eareckson for use as a forward air control aircraft, which personally flew on numerous missions.

Casco arrived in the Marshall Islands in February 1944 to tend seaplanes of patrol squadrons at Majuro and Kwajalein during the American occupation of those atolls, and later at Eniwetok until September 1944.

After overhaul at Saipan, she arrived in Kerama Retto on 25 April 1945 to care not only for seaplanes, but also for a motor torpedo boat squadron, all engaged in the American invasion and occupation of Okinawa.

Casco returning to the United States West Coast in July 1945 for upkeep, and was there when hostilities with Japan ceased and World War II came to an end on 15 August 1945.

The Barnegat-class ships were very reliable and seaworthy and had good habitability, and the United States Coast Guard viewed them as ideal for ocean station duty, in which they would perform weather reporting, law enforcement, and search and rescue tasks, once they were modified by having a balloon shelter added aft and having oceanographic equipment, an oceanographic winch, and a hydrographic winch installed.

On 23 March 1951, a Douglas C-124 Globemaster II ditched in the Atlantic Ocean after an explosion in the cargo hold, several hundred nautical miles west-southwest of Ireland and close to Casco's station.