A seaplane is a powered fixed-wing aircraft capable of taking off and landing (alighting) on water. Seaplanes that can also take off and land on airfields are in a subclass called amphibious aircraft. Seaplanes and amphibians are usually divided into two categories based on their technological characteristics: floatplanes and flying boats; the latter are generally far larger and can carry far more. These aircraft were sometimes called hydroplanes, but currently this term applies instead to motor-powered watercraft that use the technique of hydrodynamic lift to skim the surface of water when running at speed.Their use gradually tailed off after World War II, partially because of the investments in airports during the war. In the 21st century, seaplanes maintain a few niche uses, such as for dropping water on forest fires, air transport around archipelagos, and access to undeveloped or roadless areas, some of which have numerous lakes.