Dan yr Ogof (Welsh pronunciation: [ˈdan ər ˈoːɡɔv]), 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 the United Kingdom and is a tourist attraction in Wales.

[3] In a 2005 poll of Radio Times readers, Dan yr Ogof was named as Britain's greatest natural wonder.

This squeeze, known as the Long Crawl, was first passed by Eileen Davies,[5][6] a member of the South Wales Caving Club in 1963.

Peter Ogden had not descended the pitch due to lack of the required equipment and was prevented from returning by an extended period of bad weather.