Trou qui souffle

Trou qui souffle is one of the best-known cave systems in the Vercors massif, located in Méaudre, part of the commune of Autrans-Méaudre en Vercors in the Isère department. The name — literally "the hole that breathes" — comes from the strong current of air that rushes out of the rock fissures at the entrance, a natural side-effect of ventilation across a vast network of underground passages.

What makes this cave special?

This is a major karst system carved into Senonian and Urgonian limestone, ranking among the longest networks in the whole Vercors massif — its galleries stretch for dozens of kilometres, and the vertical range between the highest entrance (Toboggan des Naïades) and the deepest point (Siphon sud) reaches 670 metres. Underground rivers shaped the passages over thousands of years, and the cave still responds dramatically to heavy rain: in May 1994, a record 155 mm of rainfall in a single day pushed the water level up by 100 metres and flooded 14 kilometres of galleries, a striking illustration of how alive this underground world remains.

Systematic exploration began in the 1950s. During the 1953–1954 campaigns led by the Clan de la Verna, one of the cavers was Claude Delmotte, known among speleologists by her nickname "Cigale." From 1979 onward, the network was also studied in connection with the local water supply. Long before it became a destination for cavers, the cold air escaping from the fissures had a practical use: ice drawn from around the entrance once supplied coffee merchants in Grenoble.

How do you get there?

The entrance sits on the Route des Feuilles in Méaudre, roughly a kilometre from the village centre, right at the edge of the forest. Drive to the trailhead and follow a short forest path to reach the opening, where the cold draft is noticeable well before you get close.

What can you see inside?

There's no self-guided visit here — this is a working speleological cave, not a lit, paved show cave. Access is only possible with a guide or as part of an organised outing: a local caving association runs annual open days that let visitors discover a section of the network, while specialist caving and canyoning operators active in the Vercors area run trips scaled to different skill levels, from half-day family-friendly introductions to the demanding traverse through the Saintes de Glace section, which calls for good fitness and prior experience.

Inside, expect classic karst features: narrow squeezes, chambers carved by running water, underground streams, and visible traces of repeated flooding that has reshaped the system over millennia.

When's the best time to visit?

Guided trips run mainly from spring through autumn, when surface weather and underground water levels are most predictable. In summer, the cold air pouring from the entrance is a welcome relief after a hot hike, but the cave itself calls for proper clothing regardless of season — the temperature underground stays low and constant year-round.

Frequently asked questions

Can you explore Trou qui souffle on your own? No. It's an active speleological cave with no tourist infrastructure. Going beyond the entrance requires a guide or participation in an organised caving trip.

Where does the cave's name come from? From the strong, constant current of air blowing out of the fissures at the entrance — the natural result of ventilation through a huge network of underground passages.

How extensive is the cave system? It's one of the longest karst networks in the Vercors, with galleries stretching for dozens of kilometres and a vertical range of up to 670 metres between the highest and lowest points.

Who are the guided trips suitable for? Options range from short, beginner- and family-friendly outings covering the entrance sections to longer, more demanding traverses for experienced, fit visitors.