Huelgoat Forest
A forest of granite boulders the size of houses, piled over a river that runs unseen beneath them.
Updated 4 September 2026

AI illustration
The Chaos de Huelgoat is a jumble of granite blocks, many several metres across, heaped along a valley where the Riviere d'Argent disappears beneath them and can be heard running under the rock. The boulders are corestones, rounded by chemical weathering underground before the softer material around them eroded away, leaving them stacked. Paths thread between and over them past named features: the Trembling Rock, a block of around a hundred tonnes that can be rocked by hand at the right point, the Devil's Grotto reached down a ladder, and the Virgin's Camp. Arthurian and Breton legends attach to the whole wood.
Highlights
- The boulder chaos - house-sized granite blocks heaped along the valley.
- The buried river - water heard running beneath the rocks.
- The Trembling Rock - a hundred-tonne block that moves at one point.
- The Devil's Grotto - a chamber under the boulders reached by ladder.
When to go
April to October; the paths are slippery and the rocks treacherous when wet, which in Brittany is often. Autumn colour suits the wood. Mist adds to it and reduces safety.
Good to know
Rocks are slippery and several paths involve scrambling; falls are common. The Trembling Rock only moves if pushed at exactly the right spot. Signage is limited.
Nearby
The Monts d'Arree lie west; Carhaix is south.
What to pack for Huelgoat Forest
Chosen from what this place is for. Tap a kit for the full checklist.
- Broken-in walking shoes or boots - Grip and ankle support matter more than looks; never hike in brand-new boots. Find on Amazon
- Head torch + spare batteries - Hands-free light is essential; caves are truly dark. Find on Amazon
- Layers + a waterproof shell - Mountain weather turns fast; a packable rain jacket saves the day. Find on Amazon
- Grippy closed shoes - Cave floors are wet, muddy and slick with formations. Find on Amazon
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Opening times, ticket prices and seasonal closures change - check the official source before you go: official site.





