Many of the most highly rated, classic caves and mines are here – Gaping Gill with its almighty chasm and Porth yr Ogof with the swirling waters of White Horse Pool. Also captured are more remote, difficult to explore and seldom visited places – including the challenging-to-reach bivvy site known as Restaurant at the End of the Universe in Ogof Daren Cilau and Circus Maximus in Ogof Draenen. For pure, pristine displays of formations the wonders of Neverland in Upper Flood Swallet cannot be surpassed. Here too there are a wide range of mines, today mostly abandoned and silent. Some, such as Nenthead, contain important and intriguing industrial archaeology. Others offer an underground adventure for intrepid explorers including the Tyrolean crossings and bridges of the Croesor–Rhosydd Slate Mine or the thrilling challenges of Cwmorthin Slate Mine which will test the nerve of all comers.