The Supermarine Sea Lion II was a British racing flying boat built by the Supermarine Aviation Works. Designed by Reginald Mitchell, it was a modification of Supermarine's Sea King II. Sea Lion II was powered by a 450 hp (340 kW) Napier Lion engine. Entered for the 1922 Schneider Trophy race at Naples, Sea Lion II was planned to be able to attain a speed of 160 miles per hour (260 km/h). It competed against two Italian aircraft. flew the aircraft to victory at an average speed of 145.7 mph (234.5 km/h)—the first post-World War I success by a British aeroplane in an international competition.