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About this place
Ogof y Daren Cilau is a major cave system in south Powys, Wales, set in the limestone escarpment of Mynydd Llangatwg above Crickhowell, inside Bannau Brycheiniog (Brecon Beacons) National Park. It was found in 1957 and ranks among the longest caves in the United Kingdom. This is a destination for experienced cavers, not a sightseeing stop.
What is Daren Cilau?
The cave runs beneath a ridge that was heavily quarried from the 18th century. Stone went into buildings, lime was spread on fields, and later the rock served as flux for the region's ironworks. Surveyed passages total more than 26 km. The system lies right beside Ogof Agen Allwedd under the same hillside, and the whole of Mynydd Llangatwg carries nature conservation designations.
Why is it only for experts?
Reaching the main cave means first crawling about 517 metres through a low, tight tube. That alone keeps casual visitors out. Beyond it lie long, demanding routes where navigation is hard, trips last many hours, and a rescue would be slow and complex. Cavers also know the system for a huge passage described as the largest in Britain.
How does access work?
Rules depend on the entrance. The dry entrance, Ogof Cnwc (Price's Dig), is locked and keys are held by certain caving clubs. The Cambrian Caving Council publishes access information. The original wet entrance is not gated, but arrangements can change. Before any trip, check current conditions with the council, a club such as South Wales Caving Club, or the Mynydd Llangatwg committee.
How do you get there?
The area lies by the village of Llangattock, across the River Usk from Crickhowell. From Crickhowell, cross the bridge and climb the hillside. Abergavenny and Brecon are the nearest larger towns. The entrances sit on the slope, so bring sturdy boots and a map. Approximate coordinates: 51.83 N, 3.15 W.
What can you see without going underground?
The Llangattock escarpment gives wide views over the Usk valley and Crickhowell. You will find old quarry workings and paths along the edge, plus other cave entrances that should not be explored without a guide. Afterwards, Crickhowell has cafes and places to stay.
When should you go?
Late spring to early autumn gives the driest paths. Plan any cave trip around the weather, because heavy rain can raise water levels in the lower parts of the system.
Frequently asked questions
Can a beginner enter Ogof y Daren Cilau?
No. The cave is physically and technically demanding. Go with an experienced caver or a club.
Who controls access?
The Cambrian Caving Council publishes restrictions, and selected clubs hold keys to the dry entrance.
How long is the cave?
Sources give over 26 km of passage, placing it among the longest in the UK.
Can I enjoy the area without caving?
Yes. The Mynydd Llangatwg escarpment offers views and walks, and Crickhowell makes a good base.
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