...In the summer of 1982 Shteynberg and Lt. Colonel Gennady Zverev were conducting periodic training of reconnaissance divers, or frogmen, of the Turkestan and Central Asian military regions. The exercises had been taking place at the same Issik Kul Lake. Quite unexpectedly the officers were paid a visit by Major General V. Demyanko, commander of the Military Diver Service of the Engineer Forces of the Ministry of Defense, USSR. He arrived to inform the local officers of an event that had occurred during similar exercises in the Trans-Baikal and West Siberian military regions.
There, the frogmen had encountered mysterious underwater "swimmers," very human-like beings of enormous size (almost ten feet in height), who wore tight-fitting silvery suits despite the icy-cold water temperatures. The local commander decided to capture one of the creatures but when one frogman tried to cover the creature with a net, the entire team was propelled from deep water to the surface by a powerful force which resulted in everyone becoming stricken by aeroembolism, or Caisson Disease, caused by failing to observe the practice of decompression stops. There was only one two-man pressure chamber in the region in working condition; as a result, three men perished, and the rest became invalids.
Reference for the above text is: The Soviet UFO Files: Paranormal Encounters Behind the Iron Curtain by Paul Stonehill, p. 54, © 1998.