USS R-6 (SS-83) was an R-class coastal and harbor defense submarine of the United States Navy. Her keel was laid down on 17 December 1917 by the Fore River Shipbuilding Company, Quincy, Massachusetts. She was launched on 1 March 1919 sponsored by Ms. Katherine Langdon Hill, and commissioned at Boston, Massachusetts on 1 May 1919, with Lieutenant Commander Charles Milford Elder in command.