Brosno is a lake in the north-west of the Tver region of Russia, in the Andreepol district of the Tver region. The lake belongs to the basin of the Western Dvina and the Baltic Sea.
The area of Lake Brosno 7.2 km². Height above sea level is 243 meters, length is 10.8 km, maximum width is -4 km, average -2, length of coastline is 16.2 km. Lake Brosno is the deepest in the Tver region, its greatest depth is 41.5 meters, the average depth is 17 meters. The origin of the lake is hollow.
The lake has a shape stretched from north to south. In the central part of the lake, a large bay runs into the western shore, on the banks of which the villages Dyatkino, Gushchino and Brosno are located. The shores of the lake are dry, higher in the west, low in the east, covered with spruce-pine and birch forests, in the north and west of the lake are agricultural lands and several villages.
A kilometer north of Brosno is Lake Volkoto, from which flows the Volkota River. In the northern part of Brosno there is a source of a narrow channel flowing into Volkot. Brosno is also connected by ducts with two neighboring lakes: Dolosso (in the west) and Boyno (in the south). Lake Dolosets in the north-east of Brosno belongs to the Lovati basin, here is the watershed. Lake Brosno and its surroundings are a popular place for fishing and hunting.
According to legends, Lake Brosno is the habitat of the "dragon", a mythical animal. The origin of the legends is most likely the unusually large depth of the lake, and the processes of decay at depth, leading to the formation of hydrogen sulfide "bubbles".