Lake Baikal (Russian: о́зеро Байка́л, tr. Ozero Baykal, IPA: [ˈozʲɪrə bɐjˈkal]; Buryat: Байгал нуур, Mongolian: Байгал нуур, Baygal nuur, meaning "nature lake";) is a rift lake in the south of the Russian region of Siberia, between the Irkutsk Oblast to the northwest and the Buryat Republic to the southeast.
Lake Baikal is the most voluminous freshwater lake in the world, containing roughly 20% of the world's unfrozen surface fresh water, and at 1,642 m (5,387 ft), the deepest. It is also among the clearest of all lakes, and thought to be the world's oldest lake at 25 million years. It is the 7th largest lake in the world by surface area.
Like Lake Tanganyika, Lake Baikal was formed as an ancient rift valley, having the typical long crescent shape with a surface area of 31,722 km2 (12,248 sq mi). Baikal is home to more than 1,700 species of plants and animals, two thirds of which can be found nowhere else in the world and was declared a UNESCO World Heritage Site in 1996. It is also home to Buryat tribes who reside on the eastern side of Lake Baikal, rearing goats, camels, cattle and sheep, where the regional average temperatures vary from a minimum of −19 °C (−2 °F) in winter to maximum of 14 °C (57 °F) in summer. Lake Baikal is nicknamed "Older sister of Sister Lakes (Lake Khövsgöl and Lake Baikal)".
The Vega Gull, East Siberian Gull, or East Siberian Herring Gull (Larus vegae) is a large gull of the Herring Gull/Lesser Black-backed Gull complex which breeds in North-east Asia. Its classification is still controversial and uncertain. It is variously treated as a separate species, as a subspecies of American Herring Gull (L. smithsonianus) or included with both the American Herring Gull and European Herring Gull in L. argentatus. The Mongolian Gull, Larus mongolicus, has previously been regarded as a subspecies of the Caspian Gull (L. cachinnans) but is now sometimes lumped with the Vega Gull.