During the Cold War, the Soviets made a new type of vehicle called a ground effect vehicle (GEV). These vehicles earned their own classification because they aren't quite airplanes or hovercrafts but something in between.
Ground effect is the aerodynamic interaction between the wings and the surface of the Earth, which reduce the drag and lead to greater cruise efficiency, according to AVweb. Pilots simply describe it as "floating."
Although the Soviets didn't discover the ground effect phenomenon, they did take full advantage of it by making these behemoth low-flying vehicles.