In 1940 Northrop received an order from a Norwegian Buying Commission for the design and construction of a single-engine monoplane patrol bomber with twin floats. The Norwegian order covered 24 aircraft, and in less than eight months the Northrop N-3PB prototype flew, on 1 November 1940, powered by an 895kW Wright Cyclone GR-1820 radial engine. It attained a speed of 414km/h and was then claimed to be the world's fastest military seaplane.
Norway was invaded by the Germans shortly after the contract had been awarded, and the N-3PBs were delivered to a unit of the Royal Norwegian Naval Air Service, operating as an RAF unit from unimproved coastal sites in Iceland on anti-submarine patrol and convoy escort duties. All maintenance had to be performed in the open, often under extremely harsh environmental conditions, and during 19 months of 1941-42 several were lost during water landings in severe arctic weather, but there were no losses due to enemy action.
An aircraft was destroyed as late as 1965, in the collapse of a snow-laden hangar, but in the early 1980s an N-3PB was located and restored in Norwegian colours by the manufacturers.