Lake Baikal - 31,500 Square Kilometers

lake from the Northern Hemisphere, Lake Baikal, also called “Nature’s Lake”, is a rift lake (Lakes formed due to movements within a tectonic rift zone) situated north of the Mongolian border in Russia’s southern Siberian region, between the Russian states of Buryat Republic and Irkutsk Oblast. Lake Baikal is the world’s largest ice-free freshwater lake, and contains around 20% of world’s total fresh water. It is also considered to be one of the ‘clearest’ lakes in the world. Along with being the 7th largest lake in the world, with a total surface area of 31,500 km², it also the world’s largest lake by volume, and the world’s deepest lake. It may even be one of the oldest lakes on our planet, with an age estimated to be no less than 25 million years. The average depth of this lake is 744.4 m, with its deepest point being 1642 meters (rift lakes are typically deeper compared to non-rift ones, due to the depths of the rifts formed by tectonic movements which the waters fill). It is called the “Galapagos of Russia owing to the isolation from humans and longstanding age that have made home to some of the most varied and unusual fresh water fauna in the world. The basin of this lake is situated entirely in Russia, and its primary sources of inflow are the Barguzin, Selenge and Upper Angara Rivers. It is drained entirely by the Angara River.

source by http://www.worldatlas.com/articles/10-largest-lakes-in-the-world.html