Over the course of the expedition, which started in late July, scientists will conduct around 160 dives in various areas of the lake. Research will include gathering information on tectonic plates and a search for archeological artifacts.
Arnold Tulokhonov, director of the Baikal Institute of Nature Management at the Russian Academy of Sciences said "the deepest dive made by the Mir-1 and Mir-2 has so far been 1,608 meters."
There is no precise information about the deepest point of Baikal, which is accepted to be the world's deepest freshwater lake. Two sources most popular among scientists offer 1,637 and 1,642 meters as the deepest point.
However, making a record deep dive is not the main goal of the expedition, expedition head Artur Chilingarov said earlier.
Scientists taking part in the expedition have stressed that research is aimed at protecting Baikal's unique ecosystem.
The first stage of the expedition, which finished Sunday, focused on the middle of the lake, where scientists took samples of organisms and sediments, and discovered cracks in the bedrock from which crude oil seeps into the lake.
The second stage, starting Wednesday or Thursday, will examine the lakebed where the Selenga River flows into Baikal on the southeastern shore.
The lake has been the focus of major environmental scares in recent years, with a last-minute change to an oil pipeline route that was set to pass near Baikal's shores, and environmental regulators' claims against a pulp mill accused of pumping large volumes of toxic waste into the lake.
Baikal is the world's oldest lake, with an age estimated at 25 million years. A UNESCO World Heritage site, the lake holds around 20% of the planet's freshwater.
