The USS S-2 (SS-106) was a United States Navy submarine, part of the S-class fleet. Launched on March 1, 1920, she was designed for coastal defense and reconnaissance missions. The submarine was equipped with torpedoes and had a displacement of around 1,000 tons when submerged. During her service, the USS S-2 operated primarily in the Atlantic and Pacific Oceans. She was decommissioned on June 30, 1931, after a decade of service. The submarine is notable for being one of the early vessels in the U.S. Navy's submarine program, contributing to the development of underwater warfare tactics.