Like the neighboring massifs of Maures and Tanneron, the Estérel is a relic of the Varisque range. This crystalline massif of volcanic origin is crossed by a vast network of faults oriented north-south and west-east following the directions of the collapse ditches in which flow rivers such as the Argens, its tributary the Reyran, or the Agay. The Massif de l'Estérel falls into the Mediterranean Sea between Saint-Raphaël (Var) and Mandelieu (Alpes-Maritimes).