Following World War II, their use gradually tailed off, partially because of the investments in airports during the war. In the 21st century, flying boats maintain a few niche uses, such as for dropping water on forest fires, air transport around archipelagos, and access to undeveloped or roadless areas. Many modern seaplane variants, whether float or flying boat types are convertible amphibians—planes where either landing gear or flotation modes may be used to land and take off.