South Wales CaveFest – Detailed Cave Descriptions

Our Cave descriptions are taken from the fabulous website ‘Caves of South Wales‘


Experience Level : Novice Cavers

Ogof Clogwyn

Ogof Clogwyn is a short but easily accessible cave in the Clydach Gorge that exhibits some fine examples of phreatic shelving in the main stream passage.
Length 352m
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Eglwys Faen

Eglwys Faen is located along the Llangattock tramroad about 1000m to the west of the Chelsea Speleological Societies Cottage Whitewalls. Following the tramroad around the mountain a large bend is encountered with some old quarries on the bend. It is in the rock outcrop on the bend that the numerous entrances to this cave can be found. This very accessible cave has numerous entrances and a variety of passages from the large Main Chamber through to short crawls making this cave a great introduction to caving.

Length 1340m
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Ogof Dwy Sir

Ogof Dwy Sir also known as Quimps Quarry Cave is a short cave intersected by quarrying on Gilwern Hill. The cave is linear and is extremely dry throughout. The cave is undoubtably related to Ogof Draenen who’s Northern extremities lie close to this cave.

Length 296m
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Bridge Cave

Bridge Cave starts as a low crawl, but after a short distance having passed through a boulder choke opens out into an impressive section of streamway. This then quickly reduces in size and reaching a sump less than 300m from the entrance.
Length 311m
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Experience Level : Intermediate Cavers

Ogof Gwaliau Gwynion

Ogof Gwaliau Gwynion also known as Channer’s Dig is a cave extended by digging from the early 1970s onwards. The cave currently ends close to, but slightly lower than Puzzle Passage in the nearby Daren Cilau system.
Length 184m
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Ogof Pen Eryr

This linear cave has several interesting tight squeezes which makes it quite popular as a cave to introduce people to caving in.
Length 426m
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Ogof Craig a Ffynnon

Ogof Craig a Ffynnon is a resurgence for some of the water from Llangattock Mountain, the spring lending its name to both the old Inn below and the cave. This finely decorated cave is gated to preserve the formations and offers a range trips from gentle photographic forays to longer and more sporty trips to the Promised Land at the end of the system.
Length 8,000m
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Shakespeare’s Cave

Shakespeare’s Cave is a short but wet and sporting cave located in the Clydach Gorge. With other short caves located in walking distance from this one, it generally makes part of an itinerary for a warm Summer’s Day.
Length 365m
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Ogof Cnwc

This cave was once known as Price’s Old Dig, although Brian Price referred to it as Ogof Cnwc. It has more widely been referred to as Ogof Cnwc after 2002 when it was connected to Busman’s Holiday in Ogof Daren Cilau. The cave provides an alternative and muddy means of access to the Busman’s Holiday and Antler Passage area of Daren Cilau, whilst also providing the option of a through trip from Daren Cilau.
Length 120m to the connection with Daren Cilau
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Ogof Draenen

Ogof Draenen is one of the largest cave systems in the country and through the sporting entrance series offers a wide variety of trips.
Length 70,000m+
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Agen Allwedd

Agen Allwedd also known simply as Aggy is the longest cave system on Llangattock. The cave is a famous roost for bats which can be seen roosting in the side passages of the entrance series in the winter months. The cave system is one of the longest in the country with over 30km of passages and as such offers a number of classic caving trips.
Length 30,000m +
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Ogof Ffynnon Ddu 1

Ogof Ffynnon Ddu 1 or OFD1 as it is more often abbreviated to has one of the finest streamways of any cave in the country. This stream cuts through the jet-black limestone producing impressive cascades, deep pots and superbly scalloped walls. From the stream a route can be taken through to Cwm Dwr, OFD2 and the further reaches of the system, or you are able to climb up into the higher fossil passages to complete the Escape Route and one of the best round trips available.
Length 60,600m – approximate length of the entire OFD system
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Ogof Ffynnon Ddu 2

Ogof Ffynnon Ddu II or OFD2 as it is often referred to is the most complex and extensive sections of the OFD cave system. The entrance is located on the mountainside above Penwyllt and gives access to a vast maze of passages formed on three distinct levels. The large amount of dry fossil passages make this cave a very popular location in wet weather as there are numerous areas of cave to explore without entering the streamway. In normal weather the magnificent streamway can be reached and provides the route to Cwm Dwr and OFD1 allowing the most impressive through trips in the country.
Length 60,600m – approximate length of the entire OFD system
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Little Neath River Cave

Little Neath River Cave affords one of the most classic dry weather caving trips in South Wales. Following water from the river through the small entrance passages coupled with the long swim through The Canal makes for an exhilarating and sporting trip.
Length 8,800m
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Experience Level : Experienced Cavers

Ogof Capel

Ogof Capel is a fine stream cave that has a profusion of wonderful formations along the whole length of the 700 metres of streamway. The cave is gated and a leader system operates to preserve this vulnerable cave.
Length 835m
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Daren Cilau

Daren Cilau is one of the most extensive cave systems in South Wales with its 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 wonderful arrays of formations 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+
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Dan Yr Ogof

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 +
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Otter Hole

Possibly the most famous of all the area’s caves, Otter Hole runs below Chepstow Racecourse, and contains some of the country’s finest cave formations.

The entrance to the cave lies beside the banks of the River Wye, which is tidal at this point. The entrance series is affected by the rise and fall of the tides, which forms a sump for three hours either side of high tide. During very high tides, the whole entrance series can flood, a fact discovered by a group of explorers during the 70s who luckily managed to escape the rising waters.

One of the lasting memories of an Otter Hole trip is the incredibly thick, sticky estuarine mud that gets everywhere and refuses to be washed off. Once past the muddy bits, a couple of boulder chokes are negotiated before the formations begin, increasing in size and splendour until the Hall of the Thirty is reached, jammed with monumental stalagmites. The formations continue beyond the Hall of Thirty until the cave changes character at the junction of Tunnels Left and Right.


“The cave is one of the most serious undertakings in the country, mainly due to the complications of the tidal sump, and should only be attempted by experienced cavers” (Caves of South Wales guidebook)
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Wigpool Iron Mine

Saturday Only


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Noxon Park Mines

Sunday Only


51°44’56.3″N 2°35’17.5″W  51.748970, -2.588180