The O3U-1 was an American observation seaplane introduced in 1930. It replaced earlier models such as the O2U series, featuring an improved design. By incorporating many features of the O2U while improving engine performance, equipment, and aerodynamics, the design provided a cost-effective upgrade that impressed the US Navy. The aircraft was produced in several variants, from the O3U-1 to the O3U-4, each successive model incorporating incremental improvements such as enhanced structural strength and better engine performance. A total of 289 O3U aircraft of all variants were built until 1936. These aircraft were operated by the US Navy during the interwar period, with some of the improved variants still in service at the outbreak of World War II. Additionally, China purchased 21 O3U aircraft, which were used in bombing operations during the Second Sino-Japanese War.

The O3U-1 was introduced in Update 2.39 “Dance of Dragons” as a shipboard reconnaissance aircraft. This biplane is lightly armed, featuring no forward-firing weapons and a single 7.7 mm Lewis machine gun operated by a rear gunner. For ordnance, it can carry two 100 lb bombs. Due to its suspended armament, this aircraft is effective against small coastal vessels, which often lack the capability to retaliate effectively. However, its biplane design and relatively slow speed make it a fragile and easy target for better-armed ships.