HMS Ariadne was a Diadem-class protected cruiser of the Royal Navy, which was launched in 1898, In March 1913, she was converted to a stokers' training ship and in 1917 was converted to a minelayer and assigned to the Nore Command. She was torpedoed and sunk off Beachy Head by the German submarine UC-65 (Otto Steinbrinck) on 26 July 1917.