The Alpes-Maritimes boast a wealth of chalk mountains and underground caves: plateau de Caussols, montagne de l’Audibergue, le Cheiron and the plateaus of Saint-Cézaire (Grasse foothills).
In Roya Bévéra, the chasm of the Massif du Marguareis – which owe their reputation to the experiences of Michel Siffre – are renowned for sporting speleology. A wild mountain range, with technically demanding chasms, this isn't for beginners...