Lake Baikal is the world's second most voluminous lake, after the Caspian Sea. It is the most voluminous freshwater lake in the world with an average depth of 744.4 m (2,442 ft) and contains a total of roughly 20 percent of the world's surface fresh water. Located in the south of the Russian region of Siberia (between Irkutsk Oblast to the northwest and the Buryat Republic to the southeast, near the city of Irkutsk), the body of water is also known as the "Blue Eye of Siberia".

 

At 1,642 meters (5,390 ft), Lake Baikal is the deepest, and among the clearest of all lakes in the world. At more than 25 million years old, Baikal is also the world's oldest lake. 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, less than that of Lake Superior or Lake Victoria. 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 goat, camel, cattle and sheep, where the regional temperature varies from a minimum of -17°C in winter to maximum of 14°C in summer.

 

 

Geography and hydrography
 
Lake Baikal was known as the "North Sea" in historical Chinese texts. It was situated in the then Xiongnu territory. Very little was known to Europeans about the lake until the Russian expansion into the area in the 17th century.

 

The Trans-Siberian railway was built between 1896 and 1902. The scenic railway around the southwestern end of Lake Baikal required 200 bridges and 33 tunnels; until its completion, a train ferry transported railcars across the lake (from Port Baikal to Mysovaya) for a number of years.

 

As the railway was being built, a large hydrogeographical expedition headed by F.K. Drizhenko produced the first detailed atlas of the contours of Baikal's depths. Known as the "Galápagos of Russia", its age and isolation have produced some of the world's richest and most unusual freshwater fauna.

 

Lake Baikal is in a rift valley, created by the Baikal Rift Zone, where the crust of the earth is pulling apart. At 636 kilometers (395 mi) long and 79 kilometers (49 mi) wide, Lake Baikal has the largest surface area of any freshwater lake in Asia (31,722 km2/12,248 sq mi) and is the deepest lake in the world (1,642 m/5,390 ft). The bottom of the lake is 1,186.5 meters (3,893 ft) below sea level, but below this lies some 7 kilometers (4.3 mi) of sediment, placing the rift floor some 8–11 kilometers (more than 5 miles) below the surface: the deepest continental rift on Earth. In geological terms, the rift is young and active—it widens about two centimeters per year. The fault zone is also seismically active; there are hot springs in the area and notable earthquakes every few years. The lake drains into the Angara tributary of the Yenisei.

 

Its age is estimated at 25–30 million years, making it one of the most ancient lakes in geological history. It is unique among large, high-latitude lakes, in that its sediments have not been scoured by overriding continental ice sheets. U.S. and Russian studies of core sediment in the 1990s provide a detailed record of climatic variation over the past 250,000 years. Longer and deeper sediment cores are expected in the near future. Lake Baikal is furthermore the only confined fresh water lake in which direct and indirect evidence of gas hydrates exists.

 

The lake is completely surrounded by mountains. The Baikal Mountains on the north shore and the taiga are technically protected as a national park. It contains 27 islands; the largest, Olkhon, is 72 kilometers (45 mi) long and is the fourth-largest lake-bound island in the world. The lake is fed by as many as three hundred and thirty inflowing rivers. The main ones draining directly into Baikal are the Selenga River, the Barguzin River, the Upper Angara River, the Turka River, the Sarma River and the Snezhnaya River. It is drained through a single outlet, the Angara River.

 

Despite its great depth, the lake's waters are well-mixed and well-oxygenated throughout the water column, compared to the stratification that occurs in such bodies of water as Lake Tanganyika and the Black Sea.

 

Wildlife and vegetation
 
Few other lakes can equal the extent of biodiversity present in Lake Baikal. Lake Baikal hosts 1,085 species of plants and 1,550 species and varieties of animals. More than 80% of the animals are endemic. Epischura baikalensis is endemic to Lake Baikal and the dominating zooplankton species there: 80 to 90 percent of total biomass. The Baikal Seal or nerpa (Phoca sibirica) is found throughout Lake Baikal. It is one of only three entirely freshwater seal species in the world, the other being the two subspecies of freshwater Ringed Seal. Perhaps the most important local species is the omul (Coregonus autumnalis migratorius), a smallish endemic salmonid. It is caught, smoked and then sold widely in markets around the lake.

 

Of particular note are the two species of golomyanka or Baikal oil fish (Comephorus baicalensis and C. dybowskii). These long-finned, translucent fish normally live in depths of 200 to 500 meters (660–1,600 ft) and are the primary prey of the Baikal seal, representing the largest fish biomass in the lake. They are famous for disintegrating into a pool of oil and bones when exposed to sunlight. The Baikal grayling (Thymallus arcticus baicalensis), a fast swimming salmonid, popular among anglers and the Baikal sturgeon (Asipenser baerri baicalensis), are both important endemic species with commercial value. The lake also hosts rich endemic fauna of invertebrates. Among them turbellarian worms, snails and amphipod crustaceans are particularly diverse.

 

Diverse flora are present in the Lake Baikal watershed. In some cases flora are present whose distribution extends as far west as Western Europe; for example the Marsh Thistle, Cirsium palustre, is found at Lake Baikal as part of its native range.

 

 

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