Lake Baikal reaches a maximum sounded depth of about 1,642 meters, or 5,387 feet, in its Central Basin. The mapped point lies east of Cape Izhimei on Olkhon Island at approximately 53°14′59″ N, 108°05′11″ E. Those coordinates make the figure traceable to a specific sounding location rather than a lakewide average. It is the deepest widely accepted measurement for any lake.
A depth map shows three major basins rather than one uniform trench: the North Basin reaches about 904 meters, the Central Basin contains the 1,642-meter maximum and the South Basin reaches about 1,461 meters. The figures come from the international bathymetry project that recompiled and corrected sounding data.
The deepest point lies in the Central Basin
The Central Basin extends between the Selenga Delta region and the underwater Academician Ridge near Olkhon Island. Its deepest zone is a narrow depression east of Cape Izhimei. Published mapping places the floor below the 1,600-meter contour for a much broader area than the single maximum point.
The 2006 computer-based map reports the deepest site about 22 kilometers east of the cape in a depression roughly 1.5 kilometers wide. A peer-reviewed bathymetry paper argues that substantially greater depths are unlikely within that mapped pocket, though future high-resolution surveys can refine its shape.
Coordinates and contour spacing matter when comparing values. A crewed submersible can measure one dive track precisely without crossing the map’s deepest sounding. A broad sonar survey can identify a deeper point elsewhere even if no person visits it.
The lake has three distinct basins
The North Basin has a maximum sounded depth near 904 meters. Academician Ridge and the area around Olkhon Island separate it from the Central Basin. The underwater high influences deep circulation as well as the appearance of bathymetric contours.
The Central Basin descends to 1,642 meters. South of the Selenga Delta, the South Basin reaches about 1,461 meters. Sediment delivered by the Selenga helps create a major shallow interruption between the two deep basins.
A profile drawn along the lake therefore rises and falls across thresholds. The map resembles a chain of elongated troughs, reflecting the fault-controlled geometry of the Baikal Rift rather than erosion by one river.
Underwater slopes are steepest along some faulted margins. Submerged canyons cut those slopes and deliver sediment toward the basin floor. Their local relief does not change which basin contains the deepest measured point, but it complicates any simple bowl-shaped diagram.
Why some sources say 1,637 or 1,638 meters
The value 1,637 meters came from a 1991 dive by the Pisces submersible near Olkhon Island. The crew measured a very deep point, but the dive did not necessarily cross the lowest location later represented on the compiled bathymetric map.
Survey work conducted from 1979 to 1986 had recorded 1,642 meters at a different nearby point. The underlying hydrographic data were not publicly available until after declassification in 1999. A 2026 explanation from the Limnological Institute traces how the 1,637-meter dive value and the 1,642-meter survey value entered the literature.
Some summaries round older figures to 1,638 meters. UNESCO’s heritage page gives an approximate 1,700 meters, reflecting a broad descriptive figure rather than the current mapped maximum. These numbers describe different publication histories and precision, so 1,642 meters is the appropriate modern reference for the deepest sounded point.
Depth differs from bottom elevation
Lake depth measures the vertical distance from the water surface to the bottom. The mapped lake surface is about 455.5 meters above sea level. Subtracting 1,642 meters places the deepest bed around 1,186.5 meters below sea level.
Water level changes slightly, so depth and bottom elevation should always state their reference. A bathymetric contour is normally measured downward from the lake surface datum. A topographic elevation is measured relative to sea level.
Published cross-sections often use vertical exaggeration so small changes remain visible across the lake’s great length. Readers should check the horizontal and vertical scales before judging slope steepness from a profile.
The distinction parallels ocean floor bathymetry. An ocean trench depth is measured below sea surface, while its geological elevation uses a vertical datum. Baikal begins far above sea level, yet its rift floor lies well below it.
Rifting created the deep basin
Lake Baikal occupies the active Baikal Rift Zone, where Earth’s crust is being extended. Fault-bounded blocks subsided to create deep troughs while mountain ranges rose along the margins. Sediment has accumulated for millions of years without filling the basin.
The lake is often described as roughly 25 million years old, although the modern deep-water configuration evolved through multiple tectonic phases. Earthquakes and fault movement continue in the region. The deep floor therefore reflects crustal extension plus long-term sedimentation.
A GFZ record for the new bathymetric map explains that researchers digitized older soundings, corrected them with calibrated acoustic-velocity information and integrated newer data. Sound speed matters because an incorrect water-column model shifts calculated depth.
Depth supports an exceptional water volume
Baikal is not the world’s largest lake by surface area. Its extraordinary depth makes it the largest freshwater lake by volume. Russian environmental authorities report about 23,615 cubic kilometers of water, while dataset and rounding choices produce nearby published totals.
The lake is commonly said to contain roughly one-fifth of the world’s unfrozen surface freshwater stored in lakes. The qualifier is essential. The comparison does not include most groundwater or ice and it should not be phrased as one-fifth of all freshwater on Earth.
Volume is calculated by integrating area across successive depth intervals. A single deepest sounding cannot establish it. The computer map improved this estimate by assigning corrected depths throughout the basin rather than extrapolating from the maximum.
The UNESCO World Heritage listing emphasizes the lake’s great age, isolation and unusual freshwater fauna. Depth maintains an immense cold-water habitat, but surface circulation alone does not mix the full water column every season.
Deep water still receives oxygen
Many deep lakes develop oxygen-poor bottom water when stratification prevents renewal. Baikal’s deep water remains unusually oxygenated because dense surface water sometimes descends along slopes or enters as deep intrusions.
A study of deep-water renewal describes episodic replacement and mixing below the seasonally active upper layer. The process varies among basins and years, so the lake does not simply overturn from surface to bottom twice annually.
Pressure at the deepest point is enormous, yet endemic amphipods, microbes and the Baikal seal’s prey network occupy the lake. Depth, oxygen and long isolation have created habitats unlike those in shallower lakes.
How to read a Lake Baikal depth map
Bathymetric contour lines connect points of equal depth. Closely spaced contours mark a steep underwater slope; broad spacing shows a gentler floor. A color map may group depths into 100-meter bands, which makes basin structure clear while hiding smaller canyons.
Map resolution also reflects sounding density. Closely spaced ship tracks reveal smaller terrain than widely separated profiles. Interpolation fills the gaps, so an apparently smooth area may contain unresolved features rather than a perfectly level bottom.
The deepest contour does not show total water volume by itself. Volume depends on the area within every depth band. Surface-area rankings in the largest freshwater lakes therefore produce a different order from volume rankings.
For global context, the planned world map of lakes and ponds shows where surface water collects. Baikal’s narrow outline occupies little area compared with the largest Great Lakes, but its rift profile descends farther than any other known lake basin.
