Curiosity 9 of 10
9. Lake Baikal is the deepest and oldest lake in the world
Lake Baikal, in Siberia, is more than 1,600 meters deep and about 25 million years old. It holds about one fifth of all the fresh water in lakes and rivers on the planet.
A lake with the age of an ocean
Most lakes form and disappear within a few tens of thousands of years, filled in with sediment. Baikal is much older because it sits in a rift in the Earth's crust that is still opening, by a few millimeters per year.
The deepest point reaches about 1,640 meters. Although its area is smaller than that of other large lakes, it holds more water than the five Great Lakes of North America combined, because it is very deep.
The water is very clear: at some times, you can see dozens of meters down. In winter, the lake freezes, and the ice layer becomes thick enough to support the passage of vehicles.
Isolation and age have made Baikal a home to species that exist nowhere else on the planet. For this reason, the lake was declared a World Heritage Site by UNESCO in 1996.
The clean water owes much to a tiny crustacean that exists only there, the epischura. It filters the water and feeds on algae and bacteria, and there are so many of them that together they help keep the lake clear.
Did you know? Baikal has a seal that lives in fresh water, the nerpa, which exists only there. How it reached a lake so far from the sea is still debated by scientists.
