MOSCOW, June 18 (RIA Novosti) - During a mini-submarine dive as part of the ongoing expedition in Siberia's Lake Baikal, the world's deepest lake, explorers have recovered a sensing device left in the lake during last summer's exploration work.

A Conductivity, Temperature, Depth (CTD) sensor was dropped in the southern part of the lake a year ago to monitor temperatures, salinity, and oxygen and water transparency levels.

"The sensor was found at a depth of 1,323 meters, and lifted up to a tugboat. Despite having spent almost a year underwater, the device is in perfect condition, so researchers expect that its data has been preserved for science," the expedition member said.

The Mir-1 and Mir-2 submersibles conducted 52 dives last summer, making several scientific discoveries. Notably, researchers took samples of oil that seeps through cracks in the lake's bedrock and is digested by the lake's organisms.

During the second phase of research resumed on Monday, the expedition will explore underwater methane hydrates, mud volcanoes, and the organisms living in the lake. Ecological research will also be conducted into the impact of the toxic waste released by the now-closed Baikal pulp and paper mill from the 1960s onwards.

Mir mini-subs will also conduct tests for oil reserves beneath the lake.

Lake Baikal has a coastline of over 2,000 km, and a maximum depth of 1,637 meters. It contains 83% of Russia's and 20% of the world's fresh water.