Cave Diving Expedition - Central Thailand - November 2010

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At the end of November 2010 a short cave diving expedition explored caves in Phetchabun, Chaiyaphum and Phitsanulok.

Alex Fletcher has been exploring the flooded caves of the Krabi area for over five years. This work has included dives in Tham Sra Yuon Thong, Tham Phet, Tham Khlang and Tham Sra Lek. But, as a northern British cave diver he was missing the constricted, silted, cold sumps of home. When I offered to show him some sumps up in central Thailand that I wanted to stick an amphibious caver into he jumped at the opportunity.

The first problem with diving up my way is the inability to get a fill of air unless you want to use the compressor at the local tyre depot.  However, as this is Thailand, it is possible to send a lot of kit via a man with a pickup for remarkably little cash if you are willing to wait a few days. Also, because this is Thailand, the courier firm didn't seem to mind that the four cylinders that Alex got sent up from his favourite dive shop in Ao Nang (One Stop Dive Centre) had been filled to the brim.

Alex arrived by bus quicker than the cylinders, but that wasn't a problem as we made plans over a few beers while we waited for the equipment and the rest of the team. Next to arrive was Terry Bolger from Vientiane closely followed by the cylinders. Finally Guer turned up with his crew from Saraburi Adventure (Meaow, TJ, Barr and Beer).

The site I was very keen to get Alex to look at was the Tham Yai Nam Nao Resurgence in the northern part of Phetchabun and only an hour's drive from home.  This resurgence cave has just over 100 m of canal passage leading to the large upstream sump. It is a few metres lower than the 10 km long Tham Yai Nam Nao cave system (the entrance to which is only 100 m  away) and drains a large karst area.

The older and less fit amongst us were very pleased that some youngsters had joined the team as 12 litre diving cylinders are heavy and awkward. Once we had wrestled them as far as the start of the canal we made Alex kit up so he could swim them to the sump. Whilst helping the diver put on all his paraphernalia Terry and I admitted that in over 35 and 30 years of caving respectively this was this first time we had sherpa'edfor a diver. There is nearly as much faffing as working with a photographer. Nearly, but not quite.

Alex was launched to swim up to the sump while we waded. In places the water is neck deep and is, by regional standards, a noticeably chilly 20°C. After a bit of a look around to locate the way into the sump Alex disappeared. He surfaced briefly to let the water clear having reached the elbow of the sump and then disappeared again. This time the diver was away for a lot longer and the cold water was starting to take effect on the Thai members of the support party who didn't have the benefit of a northern European layer of blubber. Just as we were about to send some folks out and take turns watching the sump Alex returned with good news. He had passed Sump One (10 m long and 5 m deep) into a low airspace canal where the ceiling height increased to walking height and a cascade.

After lunch Terry and I surveyed from the resurgence cave up to Tham Yai Nam Nao. This helped to fix the relative positions of the two caves. However, further work is required on the Tham Yai Nam Nao survey as at the moment the water has to flow 4 m uphill from the downstream sump in the main cave to get to Sump One in the resurgence cave.

This was very encouraging for our first cave dive so the next morning it was back up to Tham Yai Nam Nao. The plan was to let Alex spend two hours exploring the other side of the sump and we would then come back for him. The kitting up went smoothly and Alex set off. The rest of us used the time to resurvey the resurgence cave, including all the nooks and crannies, whilst being videoed by two cameramen as Guer was also working on making a film about caving. With almost perfect timing I was bobbing about in the sump pool at the final station when some lights appeared between my legs and Alex surfaced.

Beyond Sump One there was 40 m of the canal passage followed by 20 m of walking passage and then Sump Two.  Although this looked very divable Alex only had the large 12 litre cylinders with him which would have been very awkward to drag up the cave. Also exploring into a second sump was starting to get a bit of a long way from home. If anything had happened we would have had to call out cave divers from the Krabi area who would have taken a couple of days to reach Phetchabun.

When the survey had been drawn up it was notable that the resurgence cave is heading off at right angles to the trend of Tham Yai Nam Nao. Another observation is that back in April a lot more water was coming out of the resurgence than went into the main stream passage downstream sump in Tham Yai Nam Nao. I still think there is a lot of potential for cave in this system.

On day three I directed the team to the Khon San area in Chaiyaphum province. This was the region we explored on the first Shepton Thailand expedition back in 2000 and we still have barely started the exploration of this large karst massif. One of the very first caves we explored and surveyed was Tham Nam Lei. The monks related a story that at the end of the dry season the upstream sump opens and it was possible to follow the streamway without reaching an end. We had been back here in April 2010, but the sump was still closed.

By forcing the cars through the fields of sugar cane and bouncing off a few rocks it was just about possible to drive to within 100 m of the entrance. This was just as well as the diver still nearly melted as he did the approach walk in a 5 mm wetsuit. In the cave there was a fair amount of faffing at the long swim trying to work out how to get the kit across as everything was negatively buoyant, including the diver.

However, we did eventually get everything over the swim, past the reticulated python and up the cascades to the sump. Alex was dressed in all his jewelry and then inserted into the water. Unfortunately finding the way on wasn't as straight forward as in the Tham Yai Nam Nao resurgence. Despite descending to 8 m and then coming back up the way on was lost in an awkward area with sloping ledges in the roof and silt reducing the visibility. Once he returned to shore the kit was ripped off the diver and he was hustled out of the cave a lot quicker than on the way in.

Following this disappointment we focused our attention to the west and the caves on the edge of the Thung Salaeng Luang National Park in Phitsanulok. The stream from the 3.7 km long Tham Khang Khao was thought to resurgence from the nearby Tham Nam Tok. While most of the team videoed the cave fish in Tham Khang Khao I helped Alex carry the kit to Tham Nam Tok. Perhaps I should have read my notes a bit more closely (they said the cave draughted) as Alex kitted up, swam in and failed to find a sump.  What he did find was a couple of ducks and then a walking sized passage. No need for diving kit, though the cave was a bit British in its difficultness.

After a night in one of those motels where there are curtains so the wife can't see where you have parked the car Alex, Terry, Meaow and Barr took on the hard task of surveying into Tham Nam Tok. I had used my experience to make sure I went into Tham Khang Khao with Guer and Beer to throw a ladder down the 3 m cascade down which the stream descends. We quickly achieved this, but Guer got to the bottom of the ladder to find deep water. He now had a problem as the two others were non-swimmers. So back up he came and more fish filming was done before we surveyed out to a GPS fix so the stream cascade could be located.

Meanwhile, in Tham Nam Tok slow progress was made surveying in very awkward cave for about 100 m where the team ran out of time. A quick explore soon reached the end of the cave at a pool and no sign of the cascade down from Tham Khang Khao. To quote Terry "this is a cave to be left to the next generation of Thailand cavers". When the survey was plotted up the Tham Khang Khao stream and the Tham Nam Tok stream don't appear to be linked, but this is almost certainly due to GPS errors.

This was the end of our brief diving expedition. Although only three dives were made the results from the Tham Yai Nam Resurgence are very encouraging and plans will soon be made for a return to concentrate on this very promising cave.

I'd like to thank those who made this trip possible: Alex Fletcher (Cave Diving Group), Terry Bolger, Anukoon Sorn-ek (Guer) and his team from Saraburi Adventure – Meaow, TJ, Barr and Beer. Thanks also to Dave at the One Stop Dive Centre for filling the cylinders and getting them on a pickup.