this aircraft used the ground effect – extra lift of large wings when close to the waters surface, a maximum of three meters above the sea but at the same time could provide take off, stable “flight” and safe “landing” in conditions of up to 5-meter waves. These were originally developed by the Soviet Union as high-speed military transports, and were based mostly on the shores of the Caspian Sea and Black Sea.
see the whole gallery and write up at http://englishrussia.com/index.php/2010/03/12/ekranoplan/ but an even bigger gallery at http://acidcow.com/pics/7956-russian-tank-ship-plane-86-pics.html 