Boybuloq Cave
Boybuloq Cave (also known as Boy Bulok) is a limestone cave in Uzbekistan and the deepest known cave in Asia. It is located high in the Gissar Range of mountains, near to Dehibolo, Uzbekistan's highest village. The cave and wider area is inaccessible for much of the year due to snow. Long-known to local people because of a nearby spring the cave was first explored by speleologists in 1984. Since then expeditions have mapped of passages in the cave and reached a total depth of . The cave could potentially extend much deeper and become the deepest in the world.
Ogof Ffynnon Ddu
Ogof Ffynnon Ddu (Welsh for "Cave of the Black Spring"), also known informally as OFD, is a cave under a hillside in the area surrounding Penwyllt in the Upper Swansea Valley in South Wales. It is the second longest cave in Wales and the deepest in the United Kingdom.