|Regions \ Wales \ Black Mountain \ Llygad Llwchwr|
Grid Reference: SN 669 178
The cave entrance lies 400m or so from the road, alongside a public footpath. There is an obvious river resurging just below and to the right of the constricted entrance.
Llygad Llwchwr (meaning "Eye of the river Loughor") is a fascinating cave consisting of a dry, high level series and an active river level. The river can be accessed from the upper series in a number of river chambers that are separated by sumps. River Chamber 4 is the limit for non-divers. Upstream from here lies a fast-flowing underwater constriction known as "The Slot". In recent years, Mike Barnes has made some progress exploring here. Also in 2001, Martyn Farr and others extended an area beyond Chamber 5 away from the main flow, hoping to bypass The Slot. The dry cave they entered was named Llygad Llwchwr II and was dug into from the surface in 2010, the original route having silted up.
The water resurging here has been traced from the sites of Pwll Cwm Sych 2.5km away and also sites up to 6.7km at Herberts Quarry; Sinc Ger-y-Ffordd/Ogof y Nant and Ogof Foel Fawr. The height difference between Ogof Foel Fawr and Llygad Llwchwr is 318m. This depth potential is bigger than the vertical range of Ogof Ffynnon Ddu, which has the greatest vertical range of any cave in Britain at 308m.
Being a major resurgence, the cave has been known since earliest times. The first recorded entry was by Thomas Jenkins in 1841.