Ogof Daren Cilau

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Daren Cilau is one of the most extensive cave systems in South Wales with it's maze of magnificent passages including the Time Machine, the largest passage in the Country. The long and tight entrance crawl has protected this cave from over visitation and much of the passages are pristine with a wonderful arrays of formations in in several areas of the cave. In recent years a connection has been dug from Ogof Cnwc allowing access to Busman's Holiday at the end of Antler Passage and now offers an alternative exit to the cave.
Length 26,000m+
Altitude 399m
Grid SO 20521 15301
On a warm summer's day - 7th July 1957 Vic Howells of the BNSSS noticed a bunch of tall grass waving madly at the foot of the Darren quarry face. Pulling away the top layer of earth he found a gap between the limestone and the clay bank. John Dyer and Mel Davies dug down to reveal a scalloped nearly mud filled arch. Ian Butterworth joined the following day and they dug down five feet to reveal the 3 foot wide entrance. A pool of water accumulated in the hole they had dug and needed bailing. On the 1st of November Brian Price joined and started about cutting a trench to take the water away. At the end of the day the water had been drained and two of the Sea Scouts who were with Brian Price were sent into the cave. They reached a boulder choke after 400 feet before turning around and reappearing at the surface looking like ghouls. John Dyer returned on the 29th and laid a telephone cable into the cave so communication could be made to surface through the entrance pool. This phase of exploration ended at the calcite barriers near the end of the crawl.
British Caving Library - Interview with Ian Rolland on exploration beyond St David's Sump
British Caving Library - Interview with Rob Parker on the discovery and naming of Seventh Hour Sump
Daren Cilau is located in the base of the cliff face in one of the quarries 400m east of Chelsea Spelaeological Societies cottage - Whitewalls. The cave is approached from the car park following the path upwards and past some disused limekilns.
Llangattock Google map showing the location of Daren Cilau and other caves in the area. There are no formal access restrictions to this cave other than its notorious 550 metre entrance series. Nevertheless, please do not smoke or use carbide, and do not cause any degradation to the cave unnecessarily. Please take special care in Crystal Oxbow, where the crystals and calcite floor are especially vulnerable.
Mynydd Llangattwg Cave Management / Advisory Committee The cave is one of the longest systems in the country (over 26km) and its long, tight and arduous entrance series makes trips to its further reaches a serious undertaking. Two camps underground allow for trips to the far reaches of the system and enable digging teams to explore deep into the cave and pursue the elusive link to Agen Allwedd which lies only 75m away at their closest points. The cave system is too complex for a full description here, so I have included just and overview.
The entrance series is over 550m long and has a fearsome reputation, and although it is tight in may places and has some formidable squeezes, most people will be through it in under an hour. The end of the crawl leads into a passage that ends in a chamber with an impressive dried crystal pool. To the right here leads to the old Main Chamber, but a careful inspection of the back wall will reveal the entrance to the boulder choke behind a large slab that has peeled way from the wall. You soon drop into the large and impressive Jigsaw Passage that can be followed for some distance to the Wriggle (a vertical squeeze randomly located in a large passage) and then on to the Big Chamber Nowhere Near the Entrance. A log book is located on a large boulder in the centre of this chamber. Climbing up the boulder slope takes you to Loop Route, a large descending passage that will take you round in a circle if you were to follow it. From the top of this passage, the left leads to Epocalypse Passage while up to the right leads to Eglwys Passage and crawls to Valentines Chamber, the Time Machine and the further reaches of the cave. Also at the top of this slope is the entrance to Man in the Roof which loops around to Urchin Oxbow. Epocalypse Passage is large and in many places covered with beautiful gypsum crystals. On the left you will pass the White Company, a fine array of helictites and aragonite formations. Further along the entrance to Urchin Oxbow is seen, its entrance 2m up the wall. After passing this the Pagoda formation and a small stream at The Kitchen are met. At the nearby junction going left takes you into Antler Passage where the impressive Antler helictite formations and the other end of Urchin Oxbow is found. Continuing up Antler Passage several climbs are encountered until the boulder chokes that lead into Busman's Holiday are reached. Passing through these passages eventually leads to a connection with Ogof Cnwc (originally named Price's Dig) that now connects with this cave.
From Loop Route climbing up the slope on the right hand side leads to a Eglwys Passage a small crawl on the left. Following these passages takes you to the large Valentine's Chamber, from the bottom of which is a squeeze between boulders and a climb down into Preliminary Passage. It is from here that you will find the stainless steel ladder disappearing up into the blackness and the route on to the Time Machine. The Time Machine is the biggest passage in the UK and after 500m you drop into the Bonsai Streamway, and the route to the rest of the cave. No tackle required on the standard routes. Fixed chain ladders are now in place on the climbs in Antler Passage, you may wish to bring a lifeline.
Cambrian Cave Registry entry for Daren Cilau
Descent 61 Article - The Route to the Heart of Llangattwg Mountain | Clive Gardner
Descent 63 Article p12-14 - Daren Cilau | Clive Gardner
Descent 72 Article p19-26 - Through Llangattock Mountain | Martyn Farr
Caves of South Wales | Tim Stratford | ISBN: 1-871890-03-9 | Published by Cordee
Selected Caves of Britain and Ireland | Des Marshall - Donald Rust | ISBN: 1-871890-43-8 | Cordee
A Caver's View of the Clydach River | Theo Schuurmans | Cwmbran Caving Club
An Exploration Journal of Llangattwg Mountain | Chelsea Spelaeological Society Records V19 - 1992
A lifeline is in place alongside the 20 metre fixed stainless steel ladder in Preliminary Passage. This ladder is quite tricky near the top.
A section of the Bonsai Streamway and also Ankle Grinder and Borrowed Boots streamways will flood in wet weather.
The route out of Antler Passage and Ogof Cnwc is long and has some navigational challenges, parties have become lost trying to make an exit here as part of a through trip. The photographs and information of this page has been provided to help cavers planning trips. Caving can be a dangerous activity, if you are interested in exploring caves please join a caving club so you can enjoy a safe introduction to this sport. Local caving clubs are listed on the links page or you can visit the 'New To Caving' website for more options.
If you feel that any of the information is incorrect or should be updated please contact us.