Réserve naturelle nationale de la grotte de Hautecourt

The Hautecourt Cave National Nature Reserve is a small but scientifically remarkable protected area in the Ain department, in the Auvergne-Rhône-Alpes region, within the municipality of Hautecourt-Romanèche, roughly 80 km from Lyon. Covering just 10.22 hectares, the reserve holds an outsized historical significance: it was the first nature reserve in France ever created specifically to protect a cave. It was officially classified as a national nature reserve (RNN47) in 1980.

What is the Hautecourt cave?

At the heart of the reserve lies a karst cave set into the western face of the southern Jura range. Its gallery system stretches roughly 150 metres in total length, reaching a maximum depth of 36 metres, with a surface projection of around 1150 m². While modest in size compared to some of the larger caves in the surrounding Revermont region, Hautecourt is considered a representative example of the karst landforms typical of this part of the Jura.

Why is the cave protected?

Hautecourt is the only cave in France classified as a nature reserve specifically to protect strictly cave-dwelling (cavernicolous) fauna. Its galleries are home to terrestrial and aquatic invertebrates adapted to permanent darkness, species characteristic of the karst systems of the Jura. Their presence points to unusually stable microclimatic conditions inside the cave.

Beyond its biological value, the cave also carries notable geological interest. Inside, visitors — or rather, researchers, since public access is not permitted — can find fault mirrors marking past rock movements along geological faults, karst concretions, deposits of crystalline sand, and a variety of geomorphological features that together record the geological history of this part of the Jura.

Can the cave be visited?

No. The Hautecourt cave is not open to public access. This is a deliberate conservation decision: the fragile cavernicolous fauna living inside is highly sensitive to disturbance, including changes in temperature, humidity, light, and noise that visitors would inevitably bring. Keeping the cave closed to tourism allows this unique underground ecosystem to remain as close to its natural state as possible.

What should you know if you're exploring the area?

The reserve sits in a scenic stretch of the Ain department, in the foothills of the Jura, within easy reach of Lyon — making it a convenient stop for anyone touring the region. While the cave interior itself stays off-limits, the surrounding landscape forms part of the wider Revermont karst terrain, appreciated by nature lovers and geology enthusiasts exploring the area on foot.

Frequently asked questions

Can the Hautecourt cave be visited with a guide? No — the cave is not open to visitors in any form, since the reserve's purpose is to protect its sensitive cave-dwelling fauna.

What makes this reserve unique in France? It was the first French nature reserve created specifically to protect a cave, and remains the only one classified for the protection of strictly cavernicolous fauna.

How large is the reserve? The protected area covers 10.22 hectares, while the cave itself has about 150 metres of galleries and reaches a depth of 36 metres.

Where exactly is the reserve located? In the Ain department, within the municipality of Hautecourt-Romanèche, on the western face of the southern Jura, about 80 km from Lyon.