Which lake is the deepest in the world?

Lake Baikal is the deepest lake in the world.

Baikal reaches a maximum depth of 1,642 metres (5,387 feet), far deeper than Lake Tanganyika, the next-deepest freshwater lake. It lies in southern Siberia, Russia, inside an active continental rift where the Earth's crust is slowly pulling apart.

That geology also helps explain Baikal's unusual age and volume. Estimated to be 25–30 million years old, it is often described as the world's oldest ancient lake. Despite having a smaller surface area than Lake Superior, Baikal contains roughly 22–23% of the world's unfrozen fresh surface water by volume.

Its depth is not its only distinction. Baikal supports thousands of plant and animal species, many found nowhere else, including the endemic Baikal seal. Crater Lake is the deepest lake in the United States, while the Caspian Sea is generally classified geographically as a lake—but neither is deeper than Baikal.