The source of the Hérisson is at an altitude of 805m, and the river tumbles down the slopes in spectacular waterfalls. It rapidly reaches the gorges, descending from 255m over 3km, forming numerous waterfalls, such as the Cascade de l'Eventail. It makes for a particularly impressive sight in autumn. In the dry period, the river reveals natural stone steps, potholes and layered cave systems. Various hikes are possible (take waterproof clothing).