The Caspian Sea Monster (Ekranoplan, or “Kaspian Monster,” Russian: Экраноплан) was a ground-effect vehicle developed by the Alekseyev Central Design Bureau in the Soviet Union, leveraging wing–ground effects to achieve low-altitude flight. The designation “KM” stands for “Prototype” in Russian; Western nations first spotted this massive craft via satellite imagery—and it earned its nickname due to its colossal size and the fact that it was discovered over the Caspian Sea. With a length of 106.1 meters and a wingspan of 40 meters, the KM was powered by eight VD-7 turbojet engines, boasting a maximum takeoff weight of 495 tons and a range of 7,500 kilometers.  
Development began in the Soviet Union in 1963, with the prototype making its maiden flight in 1966. The original prototype suffered two catastrophic crashes—in 1969, when it struck the water surface, and in 1980, following an operational error. The subsequent MD-160, delivered in 1991, was equipped with NK-87 turbofan engines and anti‑ship missiles, though it never entered active service. After being retired in the 1990s, the MD-160 was repurposed as a static exhibit. In 2015, Russia resumed work on ground-effect vehicle design.