HMS R3 was a British R class submarine built at Chatham Dockyard. She was laid down on 4 February 1917 and launched on 8 June 1918. R3 was commissioned on 17 March 1919. She came too late to see any combat in World War I, like most of the other R class submarines. R3 was paid off in September 1919, then sold on 21 February 1923.