During the summer, when Lake Baikal is full of melted ice from the Siberian mountains, it is sometimes possible to see more than 130 feet (39 m) down.
Lake Baikal is the largest freshwater lake in the world (by volume) and the world's deepest lake. Somewhat crescent shaped, it is in the southern Siberia area of Russia. In 1996 it was declared a UNESCO World Heritage Site.
"Lake Baikal is the oldest lake in the world. It is home to approximately 1,700 to 1,800 endemic plant and animal species," said Jennifer Castner of Pacific Environment's Russia program. Additionally, it holds 20 percent of the world's fresh water, due to the lake's depth.
Lake Baikal features:
There are 27 mostly uninhabited islands in Lake Baikal, according to Lake Baikal.org. The largest is 45-mile-long (72 km) Olkhon, on which there are villages. About 1,500 people live there.
More than 300 streams and rivers feed into Lake Baikal, but the Angara River is the only outlet. It carries out about 60 cubic km (15.8 trillion gallons) of water per year into the Yenisei River. Eventually the water makes its way to the Arctic Ocean.
The Selenga River is the largest source of water coming into Lake Baikal. Flowing north from Mongolia, it contributes nearly 50 percent of the lake's water
Lake Baikal is the only very deep lake to have oxygenated water at its lowest depths, like the ocean, according to a 2009 article in BioScience. Additionally, the earth under Lake Baikal is heated. The cause of the heat is unknown.