On a submarine, a moveable horizontal fin angled downward or upward when the vessel is descending or ascending. It is also a highly maneuverable motorboat with its bottom rising in steps to the stern, or a hydrofoil boat that skims over the surface of the water when driven at high speed.
An airplane that can land on or take off from water; SYN. hydroplane.
Airplane capable of taking off from, and landing on, water. There are two major types, floatplanes and flying boats. The floatplane is similar to an ordinary airplane but has floats in place of wheels; the flying boat has a broad hull shaped like a boat and may also have floats attached to the wing tips.
Seaplanes depend on smooth water for a good landing, and since World War II few have been built, although they were widely used in both world wars and the first successful international airlines, such as Pan Am, relied on a fleet of flying boats in the 1920s and 1930s.
The seaplane was invented by Glenn Curtiss.