Col-des-Roches Underground Mills
Watermills built inside a cave in the seventeenth century, because the valley had water underground but none on the surface.
Updated 30 August 2026
The valley at Le Locle has no surface river - the water drains into the limestone and runs underground - so from 1652 mill builders went after it where it was, cutting chambers into the rock at a natural swallow hole and installing waterwheels underground on several levels, one above another, driving mills, a sawmill and later an oil press. It is a genuinely unusual solution and among the few underground mill complexes in Europe. The works were abandoned in the nineteenth century, partly used as an abattoir, filled with rubbish, and then excavated and restored by volunteers from 1973. Visits are guided and descend through the chambers past the reconstructed wheels.
What's there
- Waterwheels inside a cave - stacked on levels in cut rock chambers.
- A valley with no surface river - the reason the mills went underground.
- Use from 1652 - mills, sawmill and oil press over two centuries.
- A volunteer excavation - dug out and restored from 1973.
When to go
All year, with reduced winter hours. Two hours.
Good to know
Visits are guided at set times, mostly in French. It is cool and damp underground with steps. Le Locle is a working watchmaking town, not a tourist one. Check opening before travelling.
Nearby
Le Locle and La Chaux-de-Fonds, both UNESCO watchmaking towns, are close.
What to pack for Col-des-Roches Underground Mills
Chosen from what this place is for. Tap a kit for the full checklist.
- Head torch + spare batteries - Hands-free light is essential; caves are truly dark. Find on Amazon
- Comfortable walking shoes - Sightseeing means kilometres of pavement and cobbles daily. Find on Amazon
- Grippy closed shoes - Cave floors are wet, muddy and slick with formations. Find on Amazon
- A slim anti-theft daypack - Zips that close properly; keep it in front in crowds and on transit. Find on Amazon
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Opening times, ticket prices and seasonal closures change - check the official source before you go: official site.

