Located in the Monts Dore mountains, the Chastreix-Sancy Nature Reserve occupies the Southern slope of the Sancy massif. Neighbouring the Chaudefour valley, it encompasses the glacial cirque of Fontaine Salée and offers a great diversity of rocks and volcanic structures (phonolitic dome, ash flow, basalt dykes). Its fauna is mainly mountainous and its flora is particularly rich, especially in the summit areas, with nearly 1,200 taxa.