Seliger is a system of lakes of glacial origin in the Tver and Novgorod regions of the Russian Federation. Another name is Ostashkovsky, named after Ostashkov on the lake shore.
The area of the lake is 260 km ², including about 38 km² in islands (there are more than 160 on Seliger). The largest is Khachin.
The area of the whole basin is 2275 km ².
Seliger accepts 110 tributaries (the largest ones are the Krapivenca, Soroga and Sereemuha rivers), and only one Selizharivka flows from it. The lake, lying at an altitude of 205 meters above sea level, is of glacial origin. This explains its peculiar form - it is not a lake in the usual concept, but rather a chain of lakes stretching from north to south for 100 km and interconnected by short narrow channels. The shoreline with a length of more than 500 km is distinguished by its ruggedness - overgrown headlands of the headlands, deep picturesque bays deep into the land, various islands in form.
On Lake Seliger is located the Nilo-Stolobenskaya Desert.
There are 24 plaques on Seliger, the largest are Polnovsky, Ostashkovsky, Kravotynsky, Selizharovsky, Troitsky, Sosnitsky, Nizhnekotitsky and Berezovsky. Some parts of the lake bear independent names: the lakes Viasco, Velichko, Serevo, Glubokoe, Dolgoje, Svyatoi, Svatitsa and others.
The water in Seliger is very transparent, the transparency reaches 5 meters.
In Seliger, there are about 30 species of fish (commercial importance is the snail, bream, pike, zander, burbot, vendace, ide), work is being done to acclimatize the eel, peled, carp.
In the vicinity of Seliger preserved such mammals as elk, wild boar, bear, wolf, fox, hare, squirrel, raccoon, marten, beaver, bat and others.
Of the birds there is a heron, a crane, a duck, a seagull, a hazel grouse, a woodcock, a magpie, a woodpecker, a thrush, a chiffchaff, an eagle and others.