Equipped with nuclear warheads and able to blast across the sea at 340 mph, the Lun-class Ekranoplane; part plane, part boat, and part hovercraft — is a Ground Effect Vehicle (GEV).
A GEV takes advantage of an aeronautical effect that allows it to lift off with an immense amount of weight, but limits its flight to 16 feet above the waves. Its altitude can never be greater than the length of the wings.
Think of a large seabird, like a pelican, cruising inches from the water and not needing to flap its wings.
The only complete Ekranoplane now sits on the shores of the Caspian Sea.