Crater lake on the ter­ri­to­ry of the South Kam­chat­ka Fed­er­al Reserve. The reser­voir is sur­round­ed by rocky shores and impass­able thick­ets of bush­es. In size, this giant is sec­ond only to Kro­not­sky. Kuril Lake was formed more than 8 thou­sand years ago as a result of a pow­er­ful erup­tion and the sub­se­quent sub­si­dence of the earth­’s crust. At that time, pow­er­ful erup­tions occurred in the region, the ash from which is found in the soil of the Mag­a­dan region and even in South Amer­i­ca. Sci­en­tists believe that the caldera-for­m­ing erup­tion near Kuril Lake was the largest erup­tion in Kam­chat­ka dur­ing the Holocene era. The erup­tions formed a giant basin-lake, the max­i­mum depth of which is 316 meters, which is 200 meters below the lev­el of the World Ocean. Many rivers and streams flow into Kuril Lake, and one riv­er flows out, Ozer­naya.

The lake is a unique bio­log­i­cal sys­tem, and today it is one of the largest spawn­ing grounds for salmon — sock­eye salmon — in Eura­sia. Typ­i­cal­ly, young sock­eye salmon feed in lakes for one to three years, after which they migrate to the Pacif­ic Ocean, where they live for anoth­er 2–3 years and return to their native spawn­ing grounds. Mass spawn­ing of sock­eye salmon con­tin­ues from July to March. When the fish goes up against the flow of the riv­er, the water in it lit­er­al­ly boils. The num­ber of sock­eye salmon varies from 2 to 6 mil­lion indi­vid­u­als, and this attracts preda­tors, espe­cial­ly bears, for which these places are a real par­adise. At the end, more than 200 brown bears gath­er along the shores of the lake; riv­er otters and fox­es read­i­ly feed on salmon. Kuril Lake is the largest win­ter­ing place for birds of prey; there are up to 700 Steller’s sea eagles, up to 150 white-tailed eagles and about 50 gold­en eagles here, in addi­tion, sev­er­al thou­sand pairs of slaty gulls live here far from the sea. Both large birds, ducks, and even small for­est birds — puffy duck, nuthatch, and less­er spot­ted wood­peck­er — part­ly feed on sock­eye salmon or its eggs.

There are small islands in the lake: Nizkiy, Glinyany, Chay­achy. The largest island, Samang, is a kind of haven for moth­er bears and their chil­dren. Many females swim there for the peri­od of birth of their off­spring, and when they gain strength, they return to the “main­land”. Males are found here less often, but they also do not mind spend­ing the win­ter in such cozy places.

Of the fresh­wa­ter lakes of Kam­chat­ka, it is the sec­ond largest (area 12.5 x 8 km). Area: 74.720001 sq. km., vol­ume: 3597.8601 cubic meters, aver­age depth: 48.200001 m, shore length: 53.450001 m, height: 80 m.