Caspian Sea Monster

41°56′27″N 48°22′47″E / 41.9408511°N 48.3796207°E / 41.9408511; 48.3796207

KM
Artist's illustration of the KM
General information
TypePrototype ekranoplan
National originSoviet Union
ManufacturerCentral Hydrofoil Design Bureau
Designer
StatusDestroyed in 1980
Primary userSoviet Navy
Number built1
History
Manufactured1964–1966
Introduction date1964
First flightOctober 16, 1966

The KM (Korabl Maket; Russian: Корабль-Макет, literally "Ship-maquette" or "Model-Ship"), known colloquially as the Caspian Sea Monster, was an experimental ground effect vehicle developed in the Soviet Union in the 1960s by the Central Hydrofoil Design Bureau. The KM began operation in 1966, and was continuously tested by the Soviet Navy until 1980 when it crashed into the Caspian Sea.

The KM was the largest and heaviest aircraft in the world from 1966 to 1988, and its surprise discovery by the United States and the subsequent attempts to determine its purpose became a distinctive event of espionage during the Cold War.