Daren Cilau is located in the county of Powys, Wales. It is one of a series of cave systems in the Llangattock escarpment, located close to Crickhowell. Its strange 517 m (1696 feet) entrance crawl is a genuine barrier to any casual visitors and excludes the necessity for a locked gate to secure it from vandals. It has a length of 27 km (16.8 mi) and a depth of 192 m (630 feet). Two permanent underground camps have been set, due to the expanse of the passages a couple of kilometres from the doorway.