Clearwell Caves

Clearwell Caves, at Clearwell in the Forest of Dean, Gloucestershire, England, is a natural cave system which has been extensively mined for iron ore. It now operates primarily as a working mining museum. The caves are part of a Natural England designated Site of Special Scientific Interest and the Wye Valley Special Area of Conservation; the notification is due to the large number of lesser horseshoe bats. The designation includes parts of Clearwell, along with Old Bow, Lambsquay and Old Ham mine complexes.

Cave data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).