The Lun-class ekranoplan (also called Project 903) is a ground effect vehicle (GEV) designed by Rostislav Alexeyev in 1975 and used by the Soviet and Russian navies from 1987 until sometime in the late 1990s.

It flew using lift generated by the ground effect acting on its large wings when within about four meters (13 ft) above the surface of the water. Although they might look similar to traditional aircraft, ekranoplans like the Lun are not classified as aircraft, seaplanes, hovercraft, or hydrofoils. Rather, crafts like the Lun-class ekranoplan are classified as maritime ships by the International Maritime Organization due to their use of the ground effect, in which the craft glides just above the surface of the water.

The only model of this class ever built to completion, the MD-160, entered service with the Soviet Navy Caspian Flotilla in 1987. It was retired in the late 1990s and sat unused at a Caspian Sea naval base in Kaspiysk until 2020.