Ogof Craig a Ffynnon
Ogof Craig a Ffynnon (Welsh for "Cave [of the] Rock and Spring") is a cave in Wales. The cave is about 7 km in length and is located at the base of a quarried rockface in the Clydach Gorge. Water flowing out of the cave is a resurgence of water draining off Llangatock Mountain above.
Cave data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).