The cirque is a horseshoe of vertical limestone walls rising up to 700 metres from the valley floor, rimmed by around thirty waterfalls that converge into the River Giffre. It is classified as a Grand Site de France — the same designation as Mont Saint-Michel and the Gorges du Verdon — and receives around half a million visitors a year, though the scale of the place absorbs the numbers well. The road from the village ends at a car park at the cirque's base; a footpath loops around the floor of the amphitheatre, taking in the waterfalls at close range. Snowmelt in May and June turns the cascade curtain into something genuinely thunderous.
The cirque lies within the Réserve Naturelle du Sixt Fer-à-Cheval, the oldest such reserve in France, created in 1977 to protect the habitat of chamois, bouquetin (alpine ibex), and birds of prey including the golden eagle.