Thailand's Deepest Cave Now Even Deeper

In February 2010 the Shepton Mallet Caving Club returned to Ban Mani Phruk in the north of Nan province to continue exploration of Tham Pha Phueng and other caves in this area.

A couple of days in Lom Sak were spent preparing and packing for the expedition. This year we were better prepared for vertical caves with a battery drill, Hilti 8mm anchors and yet another 200m rope thanks to the SMCC committee and a Ghar Pharau Foundation grant. There was a bigger team so even more beer was loaded onto the pickups (10 boxes of Chang, plus 2 boxes of Singha for the ladies. Note for the next expedition: this isn't enough, it ran out a couple of days before we were due to leave).

After a night in Nan town the team arrived at the Ban Mani Phruk Security Development Project headquarters on the 16th Februray. The guesthouse we used last year had fallen into a state of disrepair so was used as a tackle store. We were invited to sleep up in the office building which was an improvement on the arrangements last year. Even better, we were allowed to use the hot water shower in the boss's bungalow – there was now no excuse for some folks to avoid taking a shower.

On the first afternoon Tham Pha Phueng was rigged as far as the end of the traverse on Fitch Pitch and the short 7m pitch at the end of the 'show cave' was bolted for SRT. Another group explored a track heading north-west from Ban Mani Phruk which gives access to the Tham Champi area.

Paul about to scare himself by throwing a rock down Fitch Pitch (Photo: Keith Batten)

Fired with enthusiasm we split into three teams on the first full day. Keith, Jo and Andy headed into Tham Pha Phueng for a very productive day. As well as surveying Fitch Pitch they surveyed down the streamway to a depth of -343m and found a horizontal, dry fossil series heading south from the chamber at the bottom of Fitch Pitch. After several hundred metres this ended at a pitch with a 3 second drop. A second team of Sean, Paul and Tiggy took the drill and started rigging down the 70m entrance shaft of Tham Huai Poen. Due to the inclined nature of the shaft this took several rebelays and the 94m rope ran out just as they reached the foot of the pitch. Exploration of the passage below was stopped by a short drop that needed rigging. The third team of Ivan, Phil, Martin, Neil and Ay (Ivan's maid and bag carrier) went to Tham Nam Tok Nam Poen where the slippery pitch at the entrance was rigged and the steeply descending streamway explored to a 10m pitch.

After the exertions of the first day the 18th February was to be a 'rest day'. Martin, Keith and Andy took the easy option of driving south along the ridge past the doline with Tham Nam Tok Nam Poen to see where it went. It ended at a cabbage field where a farmer kindly guided them, via a leech infested stream bed, back up the hill to a cave entrance. Keith and Andy with one small light between them explored the cave, later called Tham Din Neao (Sticky Earth Cave) as far as a boulder chamber and established the potential of the place. Meanwhile Phil, Ivan, Ay, Paul, Tiggy, Neil, Sean and Jo hired two Hmong guides and set off for a very long walk to Tham Champi via Tham Ho Chai and Tham Ho Ying. The later two caves were short, but Tham Champi was about 350m long and well decorated. A continuation of this cave was seen, but not explored, and a return is required to survey the cave. Access to Tham Champi is shorter and easier from the north-western track driven along on the first afternoon.

The next day Martin, Neil, Andy and Phil returned to Tham Nam Tok Nam Poen to survey and explore the cave. As the anchor setting tool had been left behind Andy went back to base to fetch it leaving the others to explore and survey a muddy, ascending passage just inside the entrance. This caused some confusion for Andy who rushed back down the cave as far as the 10m pitch without finding the others. In 7 hours the cave was explored and surveyed to a sump and a higher series explored to a mud choke. With a vertical range of 138m it is the 11th deepest cave in the country.

Tham Nam Tok Nam Poen:  Plan    Section

Nearby Paul, Tiggy, Sean, Jo and Keith returned to Tham Huai Poen, surveying down the entrance pitch then rigging the next pitch and following the passage down to a choke. Just before the choke a sand floored crawl was followed through to a streamway that was descended to a deep pool.

The 20th was a quiet day. Andy, Keith, Jo and Tiggy went to Cave NA0072 that had been found by Terry Bolger in 2009. Only Andy could descend the awkward climb near the entrance and he was soon stopped due to a lack of tackle in a narrow, descending rift that didn't have a noticeable air current. Meanwhile Phil, Sean, Ivan and Paul went for a drive round the south of the massif to walk up a large river looking for resurgences, but without success.

On the 21st February Jo and Andy returned to the fossil series below Fitch Pitch in Tham Pha Phueng. They completed the survey as far as the big pitch at the end then started the descent of a series of pitches off to the side of the fossil passage a few dozen metres back from the terminal pitch. Meanwhile Keith, Phil, Neil and Martin ran the gauntlet of leeches to explore and survey Tham Din Neao. After the large boulder chamber there was a squalid, wet and muddy low section into a large passage heading north into the hill. Unfortunately this passage had a lot of mud and after managing to cross two large holes in the mud floor we were stopped by a third pit. 365m of passage was surveyed.

Tham Din Neao: Plan   Section

A third group of Ivan, Ay, Paul, Tiggy and Sean set off by 4WD along the 'north-eastern' track from Ban Mani Phruk to look for the well known Tham Pha Daeng. This turned out to be an unimpressive 100m long dry cave.  Whilst asking farm labourers for directions another large cave, Tham Pha Dam, was mentioned but there wasn't time to find this cave as well.

Tiggy enjoying Tham Huai Poen (Photo: Keith Batten)

After yesterday's adventures the 22nd was another easier day for some.  Andy, Neil, Jo and Martin wandered over to the Huai Nam Dan stream sink where the three who hadn't been there before confirmed it was hopelessly blocked by the large boulder slope.  These three then had a quick look in Tham Nam Dan and again confirmed the cave is choked.  The keener cavers, Paul, Tiggy, Sean and Keith, went to Tham Huai Poen where the survey down to the terminal sump was completed and the cave derigged.  This cave is 175m deep, the fourth deepest in Thailand.

Tham Huai Poen: Plan   Section

The 23rd February was to be the last exploration day.  Martin, Phil and Sean decided to walk south from the Nam Poen doline and ended up at a Hmong farm.  From here a guide showed them the way to Tham Pon, which Phil, explored for about 100m to a streamway, and Tham Wa, which would need tackle to enter.  The guide then escorted them futher south along the path to overlook a doline where he said a stream sank, but not into a cave.  Our guide then kindly drove us back to where we had parked the car.

Back in Tham Pha Phueng the inlet below the 7m pitch was explored and surveyed by Paul, Tiggy, Keith and Neil. About 100m of passage was surveyed and Neil managed to ascend a waterfall into another 150m of stream passage to be stopped at the bottom of a 7m cascade.  The Fitch Pitch team of Jo and Andy again descended the 127m pitch to continue the descent of the pitch series at the end of the fossil series.  This opened into the fossil series terminal pitch with a 20m descent to a sump pool.  As the sides of the sump were sloping calcite Andy was unable to get off the rope.  The survey was completed to this sump at a depth of -367m, adding 61m to the depth surveyed in 2009.  Andy and Jo then derigged all the cave below Fitch Pitch.

Tham Pha Phueng: Plan – sheet 1  Plan – sheet 2  Section

Our final caving day was the 24th. Paul, Tiggy, Sean, Neil, Keith and Martin made their way down to Fitch Pitch.  Keith then descended to the end of the traverse to derig with Sean doing the rope stuffing.  The team then slowly made their way out, derigging the 7m pitch on the way.  With all the caves derigged the last afternoon was sent cleaning and fettling kit and in the evening we managed to finish all our beer (it would have been pointless to take it back down off the hill) and drink the Development Project's shop dry as well.

After nine days up on the mountain we returned to Lom Sak after another very successful expedition.  Tham Pha Phueng had been deepened to -367m and the length extended to 3,218m (the 14th longest in Thailand).  This cave still has many leads, before above and below Fitch Pitch.  The other two promising leads found in 2009, Tham Nam Tok Nam Poen and Tham Huai Poen, where explored and surveyed down to their terminal sumps.  Our knowledge of the topography of the area was improved and we confirmed that the limestone extends at least 17km from Tham Pha Daeng in the north to Tham Din Neao in the south.  Just to keep us interested and to encourage a return trip Tham Champi, Tham Pon and Tham Wa were located, but not fully explored.  There are still a lot of dolines, many with sinking streams, that we haven't looked at yet.

We would like to thank those people who made this a successful trip. Yuphin Sopha organized the camp equipment, food and booze while En, Ying, Ay and Nom did the cooking and washing – without the ‘base camp staff’ this expedition would have been a lot less fun for the cavers and their hard work is much appreciated by all of us; Yook for allowing us to use her cooking and dining facilities at the Project headquarters; Mr Phinit, Head of the Project, for allowing us to stay free of charge and to use his hot water shower; the Hmong villagers and farmers of Ban Mani Phruk for allowing us to wander around their fields and guiding us to some interesting caves. A big thank you also to the Shepton Mallet Caving Club for purchasing two 200m ropes, a drill and a CO2 meter as well as supporting previous Thailand expeditions which has resulted in a well stocked tackle store. The Ghar Parau Foundation kindly made a £200 grant to this year's expedition. Finally we'd like to thank Shepton Mallet Caving Club members Phil Warton, Phil Collett and Gerald Marangone for their donations and loans of rigging equipment, etc.

The cavers: Keith Batten, Jo Campbell, Phil Collett, Paul & Tiggy Dummer, Martin Ellis, Ivan Hollis Sean Howe, Andy Manners and Neil Walmsley.

For more photographs from this year's expediton have a look at Neil's set on Flickr.