The Mir-1 and Mir-2 manned submersibles conduct their final descents into Northern Baikal’s Frolikha Bay.  These studies stretch over five days.  Scientists have never-before studied this region in such detail.  But now, they have detected a thermal water discharge in the bay, which they find at 400 meters.  The Mir-1 manned submersible’s crew conducts biological research, and the second crew – geophysical and geochemical research.
These submersions allow the scientists to make a detailed thermal survey of the site, determining the hydrothermal field’s actual parameters (more than two square kilometers).  The teams discover a section with an extremely high geothermal content (around 20 ºС per meter).  They locate the thermal water discharges to an area where the sand and gravel pebbles are covered in bacterial mats. 
Bacterial mats are a special form of deepwater life that occurs only near the source of the various fluid discharges.  They usually occur in areas of hydrocarbon discharge.  But the previously-inspected sites of Baikal have primarily featured methane discharges.  This confronts the scientists with the question of what actually causes this event.  After all, the hydrothermal zones of mid-ocean ridges feature methane that forms in areas of elevated temperature – where the water comes in contact with hot igneous rock and other such material. 
The scientists take gas samples for tests that should help them more closely establish the period of this geothermal occurrence. 
The scientists employ the Lander probe in their work.  This device helps them measure the hydro-physical parameters and the chemical element flows, which seep into the probe through its bottom water opening.  In part, the scientists are able to establish that the hydrothermal flows occur in areas of high biochemical activity and sharply accelerated oxygen consumption.
They are also able to record methane discharges that lead to various forms of methane anomalies.  The scientists further inspect the methane plumes they discover, which end up being of fairly complex (two-layered) structure.