Caves of South Wales Dragon

Dan Yr Ogof

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Dan Yr Ogof offers some of the most spectacular and varied cave passage in the country. Beyond the extensive showcave passages lies over 14 kilometers of the finest cave passage some of it noted for it's black scalloped walls in the lower series, while the upper series are some of the finest decorated chambers that can be seen in the UK.
Length 16Km +
Altitude 216m
Grid SN 83820 16000
The cave was first explored beyond the river entrance by Jeff and Ashwell Morgan in 1912. The Morgan Brothers entered the river cave and found a small passage that led up to the dry cave above. They named the cave Dan Yr Ogof after their farm that sat below the cave. The cave was explored up to the start of the lakes by use of a coracle to pass some of the pools on the way. In 1936 when caving had been taken up as a sport a visit to the area by Earnest Roberts, a Yorkshire caver recognised the potential of the cave and he and contacted a fellow caving friend Gerard Platten and members of the Mendip Exploration Society. In late Summer of 1937 they explored the cave and found a significant extension by crossing the lakes. The Morgan's purchased the land around the cave and in 1938 commenced driving a tunnel to give dry access to the cave and open it as a showcave in 1939. With the onset of the Second World War the cave was closed to the public, but used as Government store in this time. Tourism was slow to pick up after the war and it was not until the 60's that exploration picked up pace. The route into the rest of the cave took a number of years to find and it was Easter 1966 that a Long Crawl then known as the Endless Crawl was finally passed by Eileen Davies, Bruce Foster, Alan Coase, Neil Anderson and Colin Graham. At the end of the Long Crawl a pitch dropped down into a large passage that was named Gerard Platten Hall in respect of the work he had put into exploring the earlier sections of the cave. In September 1966 Terry Moon and Alan Coase climbed the rock face above The Rising to enter a passage that dropped into the streamway at the far side of The Rising entering the Great North Road and the northernmost section of the cave. The final section of the cave was discovered in April 1967 when David Judson and a party of Yorkshire cavers climbed North Aven to reach the Far North Chokes.
Dan Yr Ogof is located near the head of the Swansea Valley and a s a major tourist attraction is sign posted on all major roads in the area. The first part of the cave along with Cathedral Cave and Bone Cave form part of the Dan Yr Ogof Showcaves tourist attraction that is open to the general public from Easter to October.
Eastern Black Mountain Google map showing the location of Dan Yr Ogof and other caves in the area.
Location map - click marker to show entrance photo
The cave is a SSSI and cavers wishing to explore beyond the showcave must do so accompanied by a Conservation Warden.
The party size is 4 plus the Warden and all cavers must have BCA insurance cover.
Details of the Conservation Advisory Panel are found at the DYO-CAP Website
The Showcave ends at Bridge Chamber, where the cavers' route takes you across a series of deep lakes and cascades to a climb out of the water at Lake 4. These lakes were first passed in 1937 and the next section of cave is known as the 1937 series. A magnificent formation is seen in the passage above Pot Sump. From here the route takes you left towards Boulder Chamber where you can enter Wigmore Hall or climb up a loose and dangerous boulder slope to gain access to the August Series, a set of high level rifts and chambers. From Boulder Chamber the route takes you past Lavatory Dan, a periodic syphon and on to Straw Chamber where a diversion to Corbels Chamber through a low crawl can be taken. From Straw Chamber you pass the entrance to Ashford Price's Hall and under the Showerbath to take you to the Horse Trough and the start of the Long Crawl. This crawl first passed at Easter 1966 leads to the top of a fixed ladder pitch into Gerard Platten Hall and the start of DYO II.
Following the small stream you soon arrive at a parting of the ways on a major fault in the cave. Descending with the flow of water takes you to the Lower Series, while continuing along the main passage leads to the Crystal Pool. Using the stepping stones at the side of the Crystal Pool takes you to a rope traverse that leads to Flabbergasm Oxbow, noted for its distinctive shaped passage and ceiling to floor straws. This passage ends about 10m above the Grand Canyon and a return is made via the same route you came in. From the Crystal Pool the Grand Canyon leads off and in many places is festooned with helictites and straws. Near its end are the Candlewax Formations just before you break out into the massive passages of Monk Hall. This passage can be followed until it breaks out into Cloud Chamber named after the clouds of straws that cover the roof of this chamber. A small stream flows along the floor and following it to its source - Cascade Aven leads you to the climb up to the start of the Green Canal. At the start of the Green Canal a climb up a slope on the left leads into Hangar Passage where a route through a boulder choke takes you into a continuation that splits into Hangar North and Hangar South, both eventually choking. Back at the Green Canal a 50m swim making use of the buoyancy aids provided takes you to the final section of this passage where you wade until you reach Trenchways. To the left Trenchways leads to Avalanche corner and the top of the Abyss, while to the right is Go Faster that leads towards the Far North. As its name suggests progress is rapid through Go Faster until the passage divides at the start of Go Slower. The sandy passage to the left here ends in a squeeze through to Surprise Chamber. Go Slower starts as traverses in a rifty passage and soon reaches the Rottenstone Avens where passages to the right lead to Windows Aven and Tunnel Two. Following the main passage leads to Bat Chamber at the start of a larger passage that passes Bog Passage on the right before it ends at a sump pool at The Rising. A fixed ladder at The Rising leads to a very exposed climb up into Birthday Passage a high level passage and traverses that leads to a pitch down into the Great North Road.
The passage is now linear following a major fault in the cave an progress is fast as you head up through a boulder collapse and the entry to Pinnacle Chamber. North Bypass now takes you to the Meanders, past the impressively decorated Mostest to lead you to the bottom of North Aven. North Aven is a 17m free climb up a rock face following a fissure, in the central section there are fewer hand and footholds. This brings you to a passage that leads to the Starting Gate where two ways lead off, to the right is the aptly named Right Hand Series, while to the left leads to the Grand Hall and the Far North Chokes, the current limit of exploration of this cave.
Returning back to the Abyss a rope climb take you over the edge and down to the Elephant Hutch a very polished tube that now has a fixed stainless steel ladder in place. From the bottom of the Abyss you pass rope climbs up to Dali's Delight and to A1 Chamber before arriving at the Camel. A choice off two routes are available here, a polished climb over the hump or a tight crawl at the base following a small stream. This leads you to Thixotropic Passage named after the glutinous mud in its lower reaches. This continues until a fine cascade appears out of the roof just above a climb down to the entrance pool to Mazeways. Mazeways is a fine set of phreatic passages that are only accessible in periods of drought when the entrance pool lowers enough to allow access. The passage now heads to Lake 10 and from there to the start of Bakerloo Straight a fine section of phreatic tube. At the end of Bakerloo Straight a series of passages and climbs are followed to the left heading to the sound of water pounding in the Washing Machine. Traversing around this foaming mass of water leads you up the sandy floored passage to the start of Virgin Passage. A climb down gour pools takes you into some partly flooded passages where you wade across the pools. This ends above a pot that leads down to Lake 8, keeping to the left a passage is taken that leads to a small waterfall. Climbing this waterfall and following the passage above takes you back to Gerard Platten Hall and your route as you came into the cave.
Hangar Passage
Hangar Passage is a massive fossil passage that once would have carried the Giedd waters through the system. Starting near the Green Canal the passage heads to meet a massive choke, beyond which it splits into the younger Hangar North and the older Hangar South passages.

Photos of Hangar Passage - click photos for a slideshow of this area

Beside the side of the Green Canal following the climb up from Cloud Chamber a slope heads up to gain entry to Hangar Passage. Decorated with straws near the start the passage become more lofty and is followed for 200m to reach a massive choke extending far above the passage roof. On the left hand side of the choke a squeeze between boulders gives entry to the choke and by keeping left, easy passage through the long choke can be made. On emerging at the other side of the choke a passage of similar width but much lower height is reached. To the right a small stream can be followed through a low crawl to emerge after a short distance in the lofty Hangar North. This passage meanders and can be followed until the roof lowers at an area of impressive cracked mud sediments to enter the Hangar North chokes, which have yet to be passed. Back at the junction at the start of Hangar North, a passage heads upwards and to the left, being the start of Hangar South. This older passage can be followed over sediment covered boulders to arrive at a low section with sand crawls heading off. Following the flat out sand crawls you eventually arrive in a small chamber with a large boulder choke, which has yet to be passed.
Go Faster and Go Slower Passages
Go Faster and Go Slower passages allow rapid progress to the northern reaches of the cave, first via huge walking passage and then by simple traverses in a tall rift passage.

Go Faster and Go Slower - click photos for a slideshow of this area

On exiting the Green Canal you find yourself at a junction with a huge passage leading off both ways. To the left is Trenchways, defined by the progressively deeper slot in the centre of the floor of the passage. This soon reaches The Abyss and the route to the Lower Series. To the right is Go Faster Passage which is large and lofty with clean washed rock and magnificent scallops in the walls of the passage. The passage gently meanders and often pools are found on some of the large corners. Eventually the passage changes character at a junction, with a sandy slope found on the left and a short climb up to a rift on the right. The sandy passage soon decreases in dimensions and can be followed for some distance until you are forced through a tight squeeze over a boulder to enter Surprise Chamber. There is no way on from Surprise Chamber. Back at the junction and climbing up on the right allows you access to a rift, this is Go Slower Passage. This passage is tall and narrows to slot in the floor that can easily be traversed over. The traverses soon become easier and the depth of slot decreases until you are in a cobble floored passage with standing water through much of it's length, which leads up to Rottenstone Avens.
The Far North Right Hand Series
At the Starting Gate the main route heads via an increasingly large passage to eventually arrive at the Grand Hall and the Far North Chokes. The impressive nature of this passage makes this the destination of choice for most people venturing to the end of the cave. At the Starting Gate it is possible to follow a stream entering on the right and follow the much less visited Right Hand Series.

The Right Hand Series - click photos for a slideshow of this area

The route to the Right Hand Series starts very large, but soon closes down very quickly. Following the stream into the Right Hand Series you soon find a climb up into much smaller passage. The next 100m of passage is low and flat roofed with many slabs that have fallen from the ceiling. There are large banks of sediment deposits and the stream is seen intermittently. The way on is low and at times flat out crawling until a chamber is reached where the stream is regained and the water issues from a cascade. Climbing to the top of the cascade a keyhole passage can be followed by traversing in the tube above the stream. After 50m this leads into a wider stream passage that is well decorated for the next 100m. The well decorated Ice Cream Aven is passed on the left and a beyond a junction is met with a passage heading off on the left. This enters a chamber before closing down. Back at the junction with this passage the route closes down ahead to a rift and a climb up into the top of the rift leads to the final 50m of cave. Here an inlet and aven is found on the right before the final chamber is reached where 4m climb down leads to the last section of passage which is choked at both ends.
Great North Road Pitch - 15m is rigged - SRT kit is required.
A wetsuit is required if going through the Green Canal.
Dan Yr Ogof Video
Dan Yr Ogof Interactive Survey
Cambrian Cave Registry for Dan Yr Ogof
UK Caving Wiki entry for Dan Yr Ogof
Wikipedia entry for Dan Yr Ogof
Dan Yr Ogof Conservation Advisory Panel
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
The Wonders of Dan Yr Ogof | Sarah Symons | ISBN: 0862436303 | Published by Ylolfa
Dan yr Ogof - The Jewel of Welsh Caves | Martyn Farr | ISBN: 1859026451 | Published by Gomer Press
The lakes at the end of the showcave can flood to the roof in wet weather cutting off the route back into the dry showcave.
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.
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