Map: Lake Baikal is near the city of Irkutsk, in the south of the Russian country.

Formed 25 million years ago, Lake Baikal is the oldest, deepest lake in the world, reaching depths of 5,577 ft. - over a mile!

This icy oasis holds 20 percent of Earth's unfrozen freshwater supply, and sustains its own isolated wildlife species making Lake Baikal a prime site for researchers to study freshwater ecosystems and evolutionary science.

Located near the Russian-Mongolian border, you can see the lake's forested shores surrounded by snow-clad peaks of the Barguizin mountains in this photo.