This caves lies to the South of the village of Ystradfellte in Powys, South Wales.On a summer weekend inquisitive eye follow you as you force yourself into tight neoprene and wander boldly through the massive entrance that swallows the whole of the River Mellte and would probably swallow a light aircraft into the bargain!

It's a real G.R.P. (Grockle Rendezvous Point); particularly attractive as the average Tourist requires that the attraction be within a 100-yard radius of the car park. You do however have to cross a style and walk (some might say climb) down a rocky path without the luxury of handrails.

To those of the Spelaeological persuasion, the system has much to offer.No less than fifteen entrances, a large streamway,(through trip possible), dry areas, deep pools, stalagmitic formation, and the close proximity of the aforementioned car park!

Much of the system is however denied to the caver without gills as it is still under Phreatic development(itís flooded). The Cave has probably been known about for generations but the first major exploration took place in the 1930's and although the system is not massive, continues to date. Over the years I've been to PYO on many occasions and seen it under most conditions.In the bleak mid winter its setting is enhanced by an abundance of spectacular icicles.In times of flood, the water level has been within a couple of feet of the roof, normally some twelve feet above the water level.

The resurgence has somewhat of a reputation, there having been a number of deaths, attributed mainly to the undercurrents as the seemingly single source is fed from a multitude of conduits.

To the diver, perhaps the more interesting part of the system lies at the upstream end, consisting almost entirely of flooded passage.This area too has seen its share of tragedy with the death of an experienced open water diver on one of his early cave training dives.

This area also attracted our attention and so in September 1988, John and Mike McLean and I got a trip together.

We planned to dive upstream from entrance'C' through to entrance'A' or 'B', both of which would have given us a through trip. Prior inspection of the upper entrances however, revealed them to be blocked by silt and other flood debris although entrance 'A' did look as though we might have been able to dig it out. We weren't in the mood for digging and returned to the carpark to kit up having decided to enter at 'C' and "have a look upstream".

Kitting up took some time as various adjustments to harnesses and hoses were made.We all dived with two 45 or 50 Cu.ft cylinders (7 litre), side mounted with separate regulators giving two totally independent sets. Pressure gauges banded onto the upper arms, and second stages hung round the neck on lanyards. I added about six pounds of lead, which had proved sufficient on other dives. This had to be judged fairly carefully, as no other buoyancy compensation was worn - common practice for this type of sump.

Eventually we were ready and transported ourselves over the style and down to the upper entrance passing on the way a seat placed in memorial of Paul Esser who had lost his life as I mentioned earlier.His Body was never removed as it was jammed in a very low area and was impossible to recover.

We hid the car keys under a rock and went through the pre-dive ritual checking everything again and again until we were happy. I was to make a recce to see whether there was room enough for all three of us to dive together. The survey indicated a reasonable size passage but does not show much detail.

I fixed the line securely and climbed into the hole between two huge boulders. The entrance was a small gap with water issuing.I sat down, turned on my lights, fitted the regulator and contorted myself into the slot. The main difficulty proved to be the flow of water out of the slot which tried to eject me, but with a bit of effort and wriggling I got far enough forward and my legs were able to drop down. A bit more wriggling to get the cylinders in and I was away under the rock.

Pushing myself down, I was surprised to be able to see quite clearly in visibility of about two metres.I pressed on against the current laying out line from the reel.Three or four metres on, the passage dipped down to about 40cm and I had to squeeze through into another open area.The passage was about two metres in diameter. I went on a few more metres to a corner and as it showed no sign of closing, reeled in and returned to the surface, just squeezing my head out above water to report what I'd found.

John and Mike joined me a few minutes later and Mike led off, laying line which John and I followed a few metres behind. With three of us in there, the visibility reduced but remained a respectable metre or so. The passage was generally dark grey in colour with some lighter streaks and patches. The surface was scalloped, typical of passage developed under the water table.We pressed and at about 50 metres found a passage in the roof blocked with flood debris- probably entrance 'B'.Depth remained about 2 to 3 metres and after about 80 metres an obvious right hand turn was reached and further on, gaining another metre of depth we entered a vertical shaft about 1.5m diameter.Reaching the top, a mirror surface indicated an airspace - Rawlbolt airbell. John and mike managed to get their heads just above water and talk.I skulked below but could hear them talking above my exhaust noise.All OK and we pressed on. A Rawlbolt in the roof with fixed line leading on meant we could tie off the reel and leave it.This done, I lead off until at about 150metres in, we encountered a junction.Lines lead off both ahead and left.We headed left, John leading.I followed cautiously into the narrow passage, now about a metre in diameter. After 10m or so, it narrowed further. John stopped and the visibility reduced to near zero. I felt Mike at my fins - he stopped and backed off a bit. I waited a few seconds then tried to progress but John was clearly unable to make progress.I could now feel the stress rising and thought 'out'.I gave John's fin three tugs and backed slowly off - into Mike! I waited a few seconds and tried again. Mike had clearly realised the problem. John came back into me and I moved further back, firmly maintaining contact with the line.

After a couple of metres my fin became tangled in the line and I had to stop to free it.John again backed into me but stopped. Once free, I doubled up and managed to turn round by squeezing against the wall and holding the line clear. Visibility was still almost zero but I could see Mikeís lights.I made a fist of his hand and squeezed it - "out"- Mike reacted and backed off a couple more metres to the junction.John came out feet first and we floated with the current back downstream to Rawlbolt airbell. We waited a few minutes and the visibility returned to 2 metres. A short poke down the right hand passage closed down a bit. The line was tatty so we gave it a miss.

We were by now very cold. John had a free flowing regulator, one light out and another failing.Things were beginning to stack up so we untied the reel and Mike lead off, John following and me reeling.Mike was a bit buoyant and took a few goes to get back down the 3.5 metre shaft but once down we had a gentle jaunt out going with the flow.At the right angle, John reeled and I lead on. A short while later I came to the squeeze and a shaft of daylight.

It was quite a grunt getting out of the slot as there was nothing to hold on to but after removing my fins I managed to haul myself out of the water. John followed in a hail of technical Spelaeological terms followed by Mike.

At the furthest point, we were about 170 metres from base. John had found the passage constricted with silt and had not been able to see to make progress. With three of us in there, it was certainly the right decision to abort.The dive had taken 40 minutes and we'd reached a max. Depth of about six metres. We spent some time discussing what we'd seen and even more time trying to remember where, in the excitement, we'd put the car key!

Eventually it was located and we made our way back to the vehicle to de-kit and warm up lying around in the sun.

Mike and I returned the following month to try and get further but couldn't make any headway against the swollen stream.

Graham Adcock.