A floatplane (float plane or pontoon plane) is a type of seaplane, with one or more slender pontoons (known as "floats") mounted under the fuselage to provide buoyancy. By contrast, a flying boat uses its fuselage for buoyancy. Either type of seaplane may also have landing gear suitable for land, making the vehicle an Amphibious aircraft.

Floatplanes have often been derived from land-based aircraft, with fixed floats mounted under the fuselage instead of retractable undercarriage (featuring wheels).

All floatplanes tend to be less stable on water than flying boats. However, in small aircraft design, floatplanes offer an advantage over flying boats, as the hull (i .e. the lower part of the fuselage) of floatplanes does not make contact with water surfaces, permitting a conventionally-mounted single piston engine, with a propellor, in the nose.

Floats inevitably impose extra drag and weight, rendering floatplanes slower and less manoeuvrable during flight, with a slower rate of climb, relative to aircraft equipped with retractable landing gear. Nevertheless, air races devoted to floatplanes attracted a lot of attention during the 1920s and 1930s, most notably in the form of the Schneider Trophy.