Lake Pavin, in the Monts Dore in the Auvergne region, has a unique behavior in France. It appears as a double lake due to the superposition of two water strata with distinct physicochemical characteristics. Until 196 ft deep (60 m), its upper stratum has the classic characteristics of a temperate lake in terms of temperature, dissolved oxygen concentration, and pressure. Its deep layer, from 196 to 301 ft deep (60 to 92 m), on the other hand, offers much more drastic and hostile conditions. Its waters, the temperature of which does not exceed 39.2° F (4° C), are devoid of light and oxygen, and the pressure there is ten times higher than the atmospheric one.