USS S-31

The USS S-31 (SS-136) was a United States Navy S-class submarine commissioned in 1922. She was the final submarine built by the Union Iron Works in San Francisco, California.

S-31 served primarily in the Pacific Fleet throughout her career, participating in fleet exercises and training cruises. Like many of her S-class sisters, her design reflected lessons learned from World War I German U-boats. Her primary role was coastal defense and anti-shipping patrol.

During World War II, USS S-31 primarily conducted patrols off the coasts of California and Alaska. She also served in training roles, supporting anti-submarine warfare exercises.

S-31 was decommissioned in 1945 following the conclusion of World War II and was later sold for scrap. While she did not engage in direct combat actions against enemy vessels, her service contributed to the defense of the Pacific coast and the training of future submariners. Her hull number, SS-136, is a key identifier for historical records related to her activities and service.