USS S-6 (SS-111) was a second-group (S-3 or "Government") S-class submarine of the United States Navy. Her keel was laid down on 29 January 1918 by the Portsmouth Navy Yard. She was launched on 23 December 1919 sponsored by Ms. Eleanor Westcott; and commissioned on 17 May 1920 with Lieutenant Commander George B. Junkin in command. The two submarine divisions operated from Cavite over the next three years, from 1 December 1921 – 29 October 1924. During that time, they frequently visited the Chinese ports at Shanghai, Chefoo, Chinwangtao, Tsingtao, Amoy, and Woosung.