The carved names of Victor-Joconde and Jean-Joseph Maquignaz, the first to venture inside, can still be read on the walls. The gouffre des Busserailles is the point where the Marmore torrent drops into the rock, at 1,742 metres, just above the village of Singlin.
What to see
The cavity branches for 104 metres and the sheer wall of the gorge falls some thirty metres; near the entrance are three giant's kettles, the pots scoured out by spinning water. The rock belongs to the Zermatt-Saas geological unit, antigoritic serpentinites and rocks marked by eclogitic metamorphism: the same unit that slips in between Monte Rosa and the Grandes Murailles.
Visiting
The site is privately owned but open to the public, with a fitted-out walkway; it lies three kilometres from Pâquier, the main village of Valtournenche, and is reached from the regional road to Breuil-Cervinia. It is one of the Valdostan gouffres, along with Guillemore at Fontainemore, the Ratus gorge at Pontboset and the goye of Hône.
Our editors' tip
It is cold inside and the water gets you wet: bring a light jacket even in August and shoes that grip when wet. The stop is short, but it is the most direct way to understand what carved this valley.