Lake Baikal is not a basin that filled with rain. It fills a 25-million-year-old rift where the continent is being pulled apart — and the crack is still widening by millimetres every year.
Schematic map · depth shading simplified from the 2002 bathymetric survey · not to survey accuracy
Maximum depth
1,642m
The deepest lake on Earth — a little more than a mile of fresh water. Its floor sits about 1,186 m below sea level, inside a continent.
Volume23,615 km³
Share of Earth's unfrozen surface fresh water~20%
Age of the basin~25 Myr
Length × max width636 × 79 km
Rivers in / rivers out~300 / 1
Rift opening (GPS)4.5 mm/yr
01 · Depth
Nothing else on land goes this deep
Rift lakes dominate the depth rankings. Baikal beats the runner-up, Tanganyika — another rift — by 172 metres.
Baikal, Russia1,642 m
Tanganyika, E. Africa1,470 m
Caspian Sea1,025 m
Vostok, Antarctica est.~1,000 m
O'Higgins/San Martín836 m
Malawi/Nyasa706 m
Issyk-Kul, Kyrgyzstan668 m
Crater Lake, USA594 m
Vostok lies beneath ~4 km of Antarctic ice; its water depth is a radar/seismic estimate (lighter bar).
02 · Volume
One lake, more than five Great Lakes
Baikal's surface is smaller than Lake Superior's, but its depth lets it outweigh all five Great Lakes combined.
Lake Baikal23,615 km³
one lake
All five Great Lakes22,684 km³
Superior 12,100
Michigan 4,920
Huron 3,540
Ont.
Ontario 1,640 km³ · Erie 484 km³ (thin final segment). Bars share one scale. UNESCO puts Baikal at roughly 20% of the world's unfrozen surface fresh water.
03 · Cross-section
From the surface down to the rift floor
The water surface is 456 m above sea level. By the time you reach the bottom you are deep below the ocean's level — and you are still nowhere near bedrock.
0 msurface · 456 m a.s.l.
456 msea level
744 mmean depth
~1,400south basin
1,642 mdeepest point
Water vs. sediment below it, to scale
1.6 km waterup to ~7.5 km of sediment piled in the rift
1,186 m
below sea level at the deepest point (1,642 m depth − 456 m surface elevation): the floor of the deepest continental rift basin on Earth.
04 · Rivers
About 300 rivers in, exactly one out
Every inflow — from the Selenga out of Mongolia to the Upper Angara in the north — leaves through a single gap: the Angara, flowing past Irkutsk toward the Yenisei and the Arctic.
Share of river inflow
Selenga ≈ 50%
~300 other rivers ≈ 50%
Share of river outflow
Angara 100%
560,000 km²
catchment draining into the lake — an area larger than Spain, spilling across the border into Mongolia.
05 · The rift
A crack that is still opening
GPS stations either side of the lake are moving apart at about 4.5 ± 1.5 mm a year (1994–97 survey). The arithmetic below simply extends today's rate — illustrative, not a geological forecast.
4.5 mm1 year
36 cman 80-year life
4.5 m1,000 years
450 m100,000 years
4.5 km1 million years
log scale →
~25 Myr
age of the basin (UNESCO) — the oldest lake on Earth, which is why so much of its life evolved nowhere else, including the nerpa, the only seal that lives solely in fresh water.
4.5 mm/yr
measured opening of the Baikal rift, roughly northwest–southeast, perpendicular to the lake's long axis (red arrows on the map).
Why it matters · what to notice on the map
Read the shape as a fracture
The crescent is a fault line. The lake is long and narrow (636 × 79 km) because it fills a rift, not a hollow.
Three dark pools. The south, central and north basins are separate deeps; the darkest, central one holds the 1,642 m point east of Olkhon.
One way out. Trace every river: they all converge on the lake, and only the Angara leaves — so pollution that enters tends to stay for centuries.
The Selenga matters most. Half the inflow comes through one delta, carrying water — and whatever is in it — from Mongolia.
The arrows are real motion. The opposite shores drift apart a few millimetres a year; this is a young ocean basin in its earliest stage.
A fifth of the planet's usable lake water sits in one place, in a seismically active zone, beside a city of 600,000.