Russia's Mir deep submersibles made a series of dives in the world's deepest freshwater lake to inspect crystals containing natural gas on Wednesday, the Fund for the Protection of Lake Baikal said.
The dives took place near Olkhon Island, the largest island in East Siberia's Lake Baikal.
"During the dives, which lasted over 5 hours, scientists carried out experiments pertaining to the study of clathrate hydrates," the statement said.
Clathrate hydrates are water-based crystals containing methane. They are present in large volumes beneath permafrost and ocean floors.
Clathrate hydrates were found on the floor of Lake Baikal in late 1990s. Experts say the reserves are vast, although Russia has banned mineral extraction in the lake, a UN world heritage site.
The Mir manned submersibles made over 160 submersions in 2008 and 2009 as part of a scientific program to research and monitor the ecosystem in Lake Baikal.
Russian Prime Minister Vladimir Putin made a 4-hour dive in the Mir-1 submersible to a depth of 1,395 meters (over 4,500 ft) in August 2009. In a radio conversation with journalists on the surface, Putin expressed surprise at how murky the water was and called it "a plankton soup."
MOSCOW, July 28 (RIA Novosti)