The USS S-39 was a United States Navy submarine, part of the S-class fleet, commissioned in 1939. Designed for coastal defense and reconnaissance, it was equipped with torpedoes and had a displacement of about 1,200 tons when submerged. The submarine was primarily used during World War II in the Pacific Theater. Throughout its service, the USS S-39 conducted various patrols and training exercises. It was notable for its role in gathering intelligence and supporting naval operations. The submarine was decommissioned in 1945 and later sold for scrap, marking the end of its operational life.