The Supermarine Commercial Amphibian was a passenger-carrying flying boat. The first aircraft to be designed by Supermarine's Reginald Mitchell, it was built at the company's works at Woolston, Southampton, for an Air Ministry competition that took place during September 1920. Based on the Supermarine Channel, the Amphibian was a biplane flying boat with a single engine, a wooden hull, unequal wingspans and a 350 horsepower (260 kW) Rolls-Royce Eagle engine. The pilot sat in an open cockpit behind two passengers.

Supermarine was a British aircraft manufacturer. It is most famous for producing the Spitfire fighter plane during World War II. It also built a range of seaplanes and flying boats, winning the Schneider Trophy for seaplanes with three wins in a row in 1927, 1929 and 1931. After the war, the company produced a series of jet fighters.