Dan yr Ogof survey


New member
Has anyone got a DYO survey they are willing to share? They never seem to have any available to buy at The SWCC. Cheers!


New member
I was involved far back in history, but there is a BCRA publication that has a reasonably complete version. However, I do not believe it has been updated. If you visit the SWCC website you can look up and see various Newsletters with some of the newly found parts and some sketch maps (probably Grade 2 or 3 at best). Here is a reference to what you need, (1977, V. 4 No's 1 and 2). If you buy the paper copy there is a fold out version of the survey. As said, this version is by no way complete (maybe 90-95%) - and it is missing parts that were ignored after the excitement of the 1966 breakthrough. These are not major bits but all contribute to the big picture.

A bit of a rant: Someone needs to take the leadership of this and get the whole survey updated. I have a feeling that David Judson has all the original (up to 1977) survey information. The rest needs to be surveyed and added. The areas I know of need to be updated are: The Show Cave and River Cave, diving extensions and some dry. The 1937 Series (a few high level bits near avens). Gerard Platten Hall, back near the choke where the are high level extensions again and a few chambers and passages. Hangar Passage Extensions - various bits that may make it possible to connected to the Mazeways Extensions (into the tier below) Hangar North - and the Hangar South passage (which I dug for a period) and and silt fill, undulating passage that breaks through to other bits then fills again. Near the 100 ft Cascade - all high level stuff. Some nasty small passages I explored in the Right Hand Series. High level bits connected to the avens in the Left Hand Series. I do not know who at SWCC would be in touch with all of this, but I am sure someone might be interested, or already is of course. Have a great time in there, its a brilliant cave - such drama around every corner, the variety of skills needed to get to the Far North Choke and back are unique in a single cave anywhere I have been.

Stuart France

Active member
Unfortunately the Dan-yr-Ogof survey is yet another example of politics getting in the way of modern caving. I understand the original data is lost and all that remains now are the paper versions in the 1977 BCRA publication. This situation has nothing to do with SWCC.

SWCC to their credit have re-surveyed OFD during recent years for the reason that there was a disagreement with the original surveyors decades ago who then left the club along with their data.

The Draenen survey is similarly blighted. The “Grade 5” surveyors are disunited and the release of raw data and up-to-date hardcopy is blocked due to lack of collective agreement set against the background of the PDCMG management group claiming IP rights over all survey data gathered by anyone in the cave, which is of course arrant if not arrogant nonsense - but they won’t relent and so nothing gets published.

Similarly, there is unpublished and unavailable BCRA Grade 5 data for all the Llangattock caves. I’m not aware of any personal conflicts, but it seems to have become simply the norm in British caving, or at least in Wales, to withhold and generally to restrict surveys and underlying data.

As to Dan-yr-Ogof, your best bet is to visit the show cave with a camera and take a high-res picture of the nice coloured survey on a poster near the DYO entrance. Best not be noticed in case you infringe the copyright of anyone likely to throw a severe wobbly.


... PDCMG management group claiming IP rights over all survey data gathered by anyone in the cave, which is of course arrant if not arrogant nonsense ...
I just checked the PDCMG Survey policy. I think it's stretching things to say that the group claims other people's IP rights over all data. They just request that the data from any new finds goes in to a free-to-use data pool. Copyright/IP rights would still exist with the original creators, unless specifically assigned elsewhere.

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Well-known member
I thought it was being resurveyed. As I commented on another thread the significant area of Dali's Delight needs surveying as the BEC finds in the 80's don't feature.

Stuart France

Active member
The general problem is that surveying is a slow business and it needs tremendous commitment in a large cave system. Not only in Draenen, where the Grade 5 group (which doesn’t include me by the way) doing 14 hours caving trips weekend after weekend for years, but a greater amount of time later on sat in front of a computer to draw it up nicely.

PDCMG has said that a condition of access to the cave entrance where they controlled access was that all survey raw data should be handed over to them unconditionally for whatever use in perpetuity. It’s bit like saying in order to obtain cave access that any photo taken in the cave has to be copied to them in highest resolution along with all rights to its use. Obviously that kind of proposition is plain silly. Survey data doesn’t have a large market or monetary value, and nobody is doing cave surveys to make money. Put simply, PDCMG are failing to recognize the value of their huge technical achievement to the surveyors themselves and to respect that.

There is an EGM this coming weekend to review PDCMG’s entrances policy: this is a physical meeting with no online option. May I suggest that they organise another EGM pretty soon after, i.e. much faster than the 3 years it's taken to organise the entrances EGM, to review their surveying policy too. My suggestion would be to scrap it, apologize for it, and to stop conflicting with the surveyors as has been going on the past two decades and demonstrably break the survey log-jam rather than re-inforce it.

As to Dan-yr-Ogof, no there isn't any mega-project to re-survey the whole cave. Only parts of it have been resurveyed in conjunction with projects and personal interests in specific areas such as Dali's Delight, as mentioned above.


New member
Original survey notes for DYO may be lost but pretty much all the instrument readings have been freely available for years, latterly here: http://www.cave-registry.org.uk/svn/DYOcatchment/DYOSurvexData/
That is useful, but there is a lot not included, and certainly the parts explored during the last 20 years or so are spread out in all sorts of bits of writing and many not there. I doubt whether its anything more than the passage of time (which by the way is the actual cause of gravity). I think the issue is that it needs a few leaders to take the ships wheel and do this. I wonder if any single individual knows what all the unpublished bits are and how to assemble them to put the most up-to-date survey together. I am sure there is. David Judson was a surveyor/architect, and did it and Alan Coase's thesis was a stimulus to get cross sections and other vitally useful bits of information into the literature (BCRA). There are several websites that make some useful reference materials. A priority for any UK cave is that all the latest finds are surveyed and that information is documented and available for others.


Apologies that I am a little late to this conversation, but having once been an enthusiastic user and contributor to UKC I got a bit fed up with so much of the toxicity on display, and I now only occasionally check in to keep an eye on topics to which I might have an interest. Like this one.
A major resurveying project has been under way in DYO for some years. It has been done to a very high standard, but has - I believe - come to something of a halt of late.
As you will appreciate, access to DYO is very weather-dependent, and once all the nearer and more readily accessible bits of the cave had been surveyed then it became an increasingly challenging prospect to complete the further reaches and the obscure bits. The two main protagonists have not, as far as I am aware, been in the cave much of late but I hasten to add that I can't confirm this without checking the records.
I would hope that, if they are not in a position to add much to the sterling work done so far, then the surveyors might be prepared to hand over any data and relevant information to enable someone enthusiastic to take on the project. It wants doing.
If anyone has a burning desire to take this on, then please feel free to DM me and we can discuss how this might be moved forwards.
Tony, DYO Cave Advisory Panel Chair and Wardens' Sec.


New member
This discussion leaves me a little perplexed. Let me add to some things I and others have mentioned. We need a positive path forward that can stimulate people to sort things out so the future benefits and progresses.

They may be 10 or more additional explorations that need to be surveyed or if they have been they need to be added. I want to help - I spent so much time in and around the cave and its hinterland its the least I can do.

I am a long way away, but I will volunteer to be a collection manager for all that needs to be added. On the 1977 (BCRA) survey, it is a good place to begin but needs to be scanned and digitized. Anyone here know if it has been? I suppose the problem to begin with is that the various bits of survey of "recent" explorations need to be documented somewhere and eventually digitized and added to the main survey.

Stuart France

Active member
The BCRA published paper survey doesn't show spot heights (other than in example projected sections drawn apart from the plan-view survey).

I've just had a mind-numbing Click, Ctrl-S, Alt-Left-Arrow session downloading all forty .svx Survex files from Lav's folder link above and, hey, DYO.SVX then compiles OK and I can spin it in 3D in Aven and do all the rest of the display tricks with it.

Then all you have to do is to turn on "show station numbers" and find the place of interest to you. Then click in the left pane on the station name of interest that you now know the name of, and at the bottom of the list it tells you its eastings, northings and altitude referenced to OS maps.


Further to the above, I have been contacted by the two leading lights of the DYO resurveying project. Neither wishes to engage in discussion on UKC and I have been given the go-ahead to act as spokesperson. I quote:

"Over the years ( 1998 to 2017 ) [we] (plus a few others) have surveyed approx. 7 km, this might equate to 25% of the probable passage that exists. The standard is grade 5 and is time-consuming work.

"The data that has been processed is attached, you will note one or two bits have not been completed and would need additional detail to ensure that wall lines can be joined.

"[We are] quite willing to have the data that exists (and the pdf file) available to share but please be aware that [we] effectively own the data.

"We need to identify a place to deposit the survey data so others can use it but the quid pro quo must be that as other data is generated it is added to the same place."

So, I now have the PDF of the recent survey and as you can see the data is available if required.