Dan yr Ogof (Welsh pronunciation: [ˈdan ər ˈoːɡɔv]), located at the National Showcaves Centre for Wales, is a 17-kilometre (11 mi) long cave system in south Wales,about 5 miles (8 km) north of Ystradgynlais and 15 miles (24 km) southwest of Brecon, in the Brecon Beacons National Park. It is the main feature of a show cave complex, which is claimed to be the largest in Europe and is one of the major tourist attractions in Wales.[2] The first section of the cave system is open to the public, but the extensive cave system beyond is scheduled as a national nature reserve and is open only to bona fide cavers.[2]