Welcome l A Brief History l Hints and tips l Credits

 Lets go caving !  OFD l or OFD ll/lll


Welcome !

~ Ogof Ffynnon Ddu (pronounced: oh-gof-fun-on-thee in Welsh), is the deepest and 3rd longest cave in the UK.

It lies deep under a grassy, rocky hillside in the Upper Swansea Valley in South Wales. The underground river roars and tumbles along its deepening course, great sandy chambers stand still and silent, and the delicate stalactites drip quietly, and all in total darkness, even as you read this, even as we sleep. High above, sheep graze the slopes and sometimes Buzzards and even Red Kites can be seen circling overhead.

A brief history:

~ OFD was discovered in 1946 by Peter Harvey and Ian Nixon. The South Wales Caving Club was formed at that time. Peter was for a long time our Club President, and only stopped caving around 2006 in his mid eighties.
Here is a brief account of the discovery and early exploration:

High on the slopes of Fan Gyhirych it is raining. Well, this is Wales after all. Several streams rush down into a huge soggy peat bog, dotted with marsh grasses and reeds. After slower progress through this obstacle the Byfre Fechan emerges, enlivened and more acidic than before. It then promptly sinks into the mud, rocks and flood debris that is Pwll Byvre and discovers a deep band of Carboniferous Limestone to get its teeth into. The local sheep, having jumped over the stream to reach another juicy patch of grass, carry on chewing and don't give it another thought.

One thousand feet lower, in the Tawe valley, a wide rock arch disgorges a strong and languid river, dark and rich with secrets. This is the Ffynnon Ddu, the Black Spring. After rain this resurgence swells and boils as the underground river rushes into daylight. In heavy flood, unable to cope with the pressure, the river finds release by bursting out from rocky crevasses in the woods and fields nearby.


The Resurgence

 Click for a more detailed survey

Boulder Chamber

Early Explorers.
In the summer of 1946, Peter and Ian, fascinated by this promising but impenetrable resurgence, turned their attention to these occasional springs, and began to dig . . .

What they found was what we now call OFD l, a sporting and sinuous river cave, sculpted out of dark limestone. Dangerous in flood, the clean-washed high river passages are a joy to explore, as long as you know how to climb up to the high level dry passages if need be! Delighted by their new discovery, early members of SWCC were stopped in their tracks by a huge boulder pile about half a mile into the cave.

After much hard work, rock falls and determined wriggling, they broke through Boulder Chamber, only to be faced with a deep and ominous sump pool. By now it was the 1960's, and cave diving was very much in its infancy. The first underwater visitors were still at that time using "bottom walking" techniques with lead boots and heavy oxygen re-breathing apparatus. Fortunately the cross-over was beginning to diving with fins, and this allowed the early explorers much more freedom and flexibility.

Diving in Dip Sump

OFD ll Streamway

Near Top Entrance

The Connection
. Dip Sump was finally passed in 1966 by pioneering cave divers Charles George and John Osborne, who even dived carrying a ladder through, so that they could climb out at Shower Aven! The way was open into the long sought-after upper reaches of the mainstream, OFD ll. Month after month, longer and longer trips were made upwards and upwards as the cave slowly revealed her secrets. Some of the hardest work was carrying scaffold poles up the mainstream and the scaling of Maypole Inlet. Finally in September 1967, having entered through the Cwm Dwr entrance (discovered in 1963), they came to within a few feet of the surface, having traversed two miles of passage and climbed up some 700 ft, passing underneath what are now our Club cottages.

After a combination of hammer blows and early radio-communication with the surface, the underground party dug upwards pulling down soil, mud and boulders! The Top Entrance (E) was open, and with it a classic through trip. **

In the rush of exploration that followed, the connection to OFD lll was made, along with many more miles of passages. More recently the discovery of the Northern Lights has filled a blank space on the survey, but there is surely more to find.

Playground. Edge your way along daunting high-level traverses, chimney down winding canyons, slither through narrow passages, post yourself backwards through the Letter Box, wander through broad tunnels, hold your breath as you jump into deep plunge pools or stand in awe in front of beautiful calcite columns. This cave has it all.

The underground river roars and tumbles along its deepening course, it is the system's backbone as well as its creator. And if you sit alone for a while by the Gothic Sump, you will hear voices amongst the gloops, drips and splashes.

Back on the surface, the sheep are still chewing contentedly, and still don't think to ask where the stream goes.

~ The system is now 308 meters (1010 ft) deep, and has around 59 km (37 miles) of passages ~

Some Welsh names:
Ogof ~ Cave.  Ffynnon ~ Spring.  Ddu ~ Black.  
Fan Gyhirych
~ Gyhirych Mountain.  Byvre Fechan ~ Little Byvre (stream).
 Pwll Byvre ~ Byvre Pool (stream sink).  Cwm Dwr ~ Valley of Water.

** Among those present at the Top Entrance breakthrough in 1967 were: Hywell Ball, Noel Christopher, Paul Deakin, Colin Fairburn, Bruce Foster, Peter Harvey, Mike Holhead, Clive Jones, Bill Little, Henry Mares, Terry Moon, Paddy and Susan O'Reilly, John Osborne, Jem Rowland, Rod Stewart and Clive Westlake.

Would you like to follow in their footsteps? Let's go!

Read Tony Knibbs' and Eric Inson's reminiscences


The virtual tour (hints and tips):

~ My aim is to give you a real caver's eye view as you explore. To find your way, you will need to click on the link(s) hidden within each picture, to move ahead. As a clue, two small dots .. at the bottom left of any page indicate that there is more than one way to go. To date there are around 350 interlinked pages available, showing many of the actual views that you would get during 10 - 12 hours of real caving trips in this vast system. See if you can find the elusive link from l to ll or hunt for the key to the beautiful Columns formations, or make your way over the scary traverses to Smith's Armoury in OFD lll.

~ Along the way there are a number of round trips, large and small, and some blind alleys too (just like the real thing!), and the famous Through Trips (in both directions). You may also find yourself getting lost, or returning to where you started via different route! With perseverance it is possible to see it all. To assist the feeling of realism, you won't find lots of distracting menus on each page. Just photographs along with some helpful descriptions, and the occasional map to guide you.

~ I've designed the photographs to appear as fast as possible, while still giving good detail, and you will notice that if you visit any page a second time, the picture will appear almost instantaneously. (If it doesn't, check that your browser's cache is set to check automatically for visited pages.) You probably won't cover all the possible routes in your first visit, but if you return, you will find that you will be able to quickly resume your exploration from where you left off.


Happy caving
- take care of the natural environment, yourself and your fellow explorers, and do let me know in the Visitor's Book, how you got on!

*A prophecy? I was somewhat humbled, a while ago, to read in our Club's 50th Anniversary Publication (1996), the following from Peter Harvey: "So good luck! However remember, things never remain the same and it could be that in 2046 very few people will actually go caving but will experience it electronically sitting at home in some form of virtual reality ...... so enjoy your caving while you can" ~ So, do come and see it for real - come and visit the South Wales Caving Club.

Weather Warning - In the real cave the Mainstream and attempts to do the Through Trip can be dangerous in wet or unsettled weather. Always check the forecast, get local advice, and don't go there if in any doubt.
Check the weather here.



~ Felicity, Tom, Sue, Noel, Rick, Leif, Ingy, Helena, Cecilia, Eric, Martin and Volker for excellent flashgun and modelling assistance (and anyone else who has ever assisted!)

~ The South Wales Caving Club and Elsie for their support, and permission to reproduce the cave survey, to Eric for taking us to the columns and to Clive Westlake for information about the opening of Top Entrance.

~ Martyn Farr (cave diver extrordinare) for permission to use some of his underwater shots where I dare not go. www.farrworld.co.uk

~ And to the CCW who take care of some of the land overlying the cave system:


© Peter Collings-Wells 2003-2020

 Welcome l A Brief History l Hints and tips l Credits

 Lets go caving !  OFD l or OFD ll/lll