Upon returning to the United States in September, "Sea Owl" was assigned to the Atlantic Fleet and was based at Balboa in the Canal Zone as a unit of Submarine Squadron 6 (SubRon 6). From October 1946 through March 1947, she made a cruise along the west coast of South America and joined the other submarines of SubRon 6 in fleet exercises off Culebra Island in the West Indies. She next supported antisubmarine training at Guantanamo Bay, Cuba, and Key West, Fla.