20% of the world’s total unfrozen freshwater reserves are in Lake Baikal.
Incidentally, it is also the oldest and deepest freshwater lake in the world. It is 1,700 meters deep at its deepest point and is located in Irkutsk, Russia.
Source: https://whc.unesco.org/en/list/754
Photo: https://www.pexels.com/de-de/foto/eisbildung-666737/