'The Columns' Ogof Ffynnon Ddu cave, South Wales, UK"The Nave" in Ogof Ffynnon Ddu cave, South Wales, UKDinas Rock Silica Mine. the beginning of the flooded section. South Wales, UKDinas Rock Silica Mine. the beginning of the flooded section. South Wales, UKCwmorthin Slate Mine, north Wales, UKDinas Rock Silica Mine. Large chamber supported by rock pillars. South Wales, UKCwmorthin Slate Mine, north Wales, UKWinch mechanism. Dinas Rock Silica Mine. South Wales, UKCwmorthin Slate Mine, north Wales, UKRhosydd Slate QuarryCae Coch Sulphur MinePenarth slate mine, north Wales, UKCwmorthin Slate Mine, north Wales, UKRailway tracks and an incline going deeper into the Dinas Rock Silica Mine, South Wales, UKDinas Rock Silica Mine. the beginning of the flooded section. South Wales, UK"Car graveyard" Gaewern Slate Mine, Wales, UK"Car graveyard" Gaewern Slate Mine, Wales, UKA 'Straw' cave formation in Ogof Ffynnon Ddu cave, Wales, UKCae Coch Sulphur Mine, Wales, UKRhosydd Slate Quarry