Rowten Pot
Rowten Pot is one of several entrances into the 27-kilometre (17 mi) long cave system that drains Kingsdale in North Yorkshire, England. Its entrance is a shaft some 27 metres (89 ft) long, 10 metres (33 ft) wide, and at the southern end 72 metres (236 ft) deep.
Cave data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).