On the other hand, in stormy weather, its deep waters appear very dark, which undoubtedly earned it its name Pavin (from the Latin pavens, terrible).

[11] The anoxic waters of the lake bottom, between 60 and 92 meters, are confined and loaded with gases such as carbon dioxide, nitrogen, methane and hydrogen sulphide, linked to the decomposition of organic matter, which gives them a bad odour.

[5] However, ground movements (significant rock falls) or seismic events could disrupt this balance and lead to sudden degassing.

Its unaltered characteristics (meromictic lake and pristine[alpha 2]) has meant that it has been widely studied, particularly with regard to hydrobiology.

Scientific teams attached to the CNRS from Lyon, Paris, Clermont-Ferrand and Orléans launched a platform in 2013 allowing samples to be taken in the middle of the lake.

The lake would have overflowed several times during its history, the most recent event would have deposited mudslides in the Couze valley around 750 years ago; these mudflows were mapped, dated and analyzed by the two previous researchers.

[18] A similar version has it that it was God who drowned the city under torrential waters in order to punish its promiscuous inhabitants.

The climbing site, located on the western edge of Lake Pavin, is a cliff resulting from a basalt flow escaped from the Puy de Montchal, just over 1 km away.

The paths run through basalt organs where dihedrons (with large cracks at the bottom) and rectilinear pillars alternate .

Initially equipped by the Super-Besse mountain gendarmerie platoon, the site offers 24 routes20 to 25 m high, rated 4 to 6c, with predominance of levels 6a and 6b.