BO NHON – Cave of the 150 People
Our arrival in Lang Son had been greeted with clear skies and extremely British temperatures, i.e. very cold. By the time we reached our target area near the Cao Bang border, “cold” had been replaced by “warmer”, but only on account of a heavy, leaden layer of cloud. It was weather to which we are accustomed, but not in Vietnam. The windscreen wipers on the jeeps were working overtime as we drove into the heart of the Quoc Khanh karst.
Exploration during the 2001 expedition, most notably Nguom Ban San, had confirmed the existence of significant cave development on the Lang Son side of the provincial border and we now hoped to further add to the register of known caves. Our maps indicated four potential river sinks beyond Nguom Ban San and we immediately set out to investigate these features.
The weather had ensured that the tracks were only passable with care as we headed up the valley towards Ban Gi and the presumed easternmost sink of the Quoc Khanh area. The most notable hazard of the journey was not the track, but rather a lack thereof- an assortment of planks and bamboo poles laid across a stream bed. Despite having great confidence in the drivers, our bold crew took the view that being on solid ground was preferable to being in a ditch and promptly jumped out. The Vietnamese chuckled as they rattled over the bridge, no doubt wondering what we would do if there was any real danger.
At Ban Gi village, we quickly contacted the local President and Mr Phuc explained our objectives and showed our various letters of permission. We knew this point was very close to the border with China and anticipated a degree of caution from the authorities, hence we carried every official bit of paper we could muster. In the event, this was unnecessary - after tea and the obligatory rice wine, we were soon on our way to the cave.
We seemed to be getting conflicting reports regarding the nature of the cave – wet, not wet; big, not big; long, not long. In the end, we adopted the time-honoured expedition motto of “Sod it, let’s go and see”.
In fact, the Bo Nhon “sink” was a resurgence and it was heading 180 degrees in the opposite direction to that which we expected. A large entrance chamber was decorated by a very fetching concrete dam which in the wet season must hold back a considerable volume of water. We had been told that, in extremis, this entrance chamber could house up to 150 people. We quickly changed and started into the cave, along with what seemed like half the village.
A small rift traverse bypassed the lake formed by the dam and we were soon traversing gours and pools in an extremely pleasant passage. Climbs over gour dams were interspersed with traverses around deep pools. It was indeed big and wet and not short! How long remained to be seen, but the first few hundred metres certainly relieved the gloom of the weather and started to soothe the frustrations of our time in Thanh Hoa and Hoa Binh.
Initially, we were keeping a close eye on Mr Phuc as it was his first ever caving trip and we figured that an injured interpreter would not be a welcome development. A couple of climbs and traverses soon demonstrated that he was a natural and we even began to wonder who was keeping an eye on who.
Around a kilometre or so into the cave, our Kiwi note-taker’s scribbling fingers were becoming a little fatigued and a pause for lunch was taken. Straightening out the curves, we surmised that the general trend of the cave was more or less due south and we began to speculate on how it might fit into the overall hydrology of the district. As if to confirm our thoughts, as we began surveying again, the cave promptly provided us with nine 50m legs with only single figure variations from 180 degrees!
After a chamber with a spectacular pagoda-type stalagmite, the way on became wetter. Donning wetsuits, we began to wade and eventually swim towards the sound of running water. After a low, windy arch, we emerged into a streamway flowing from right to left. The sound of a cascade proved in fact to be the water pouring through a concrete dam! At this stage, we were over 2km from the entrance and marvelled at the resourcefulness of the Vietnamese. Carrying concrete all this way must have been quite an undertaking. With a good lead upstream and a less appetising prospect beyond the dam, it seemed a good point to end the day’s survey. We exited steadily, rattling off a few photos for good measure.
The following day a larger team returned to give the cave a blast. In addition to John, Paul and Woody, Sweeney was added for his expertise in pushing small wet crawly bits and Chris and Danielle for their ability to ignore ridiculous instructions such as “Stand on top of those pointy boulders with your light off” or “Can you move 7 inches left to make certain of blocking the backlight”. In reality, our attempts to do photographic justice to the entrance series were thwarted by technical faults/shortage of time/lack of enthusiasm/eagerness to get to the sharp end (delete as appropriate).
Woody and Sweeney ticked off the short passage up to a second entrance and then began the downstream lead. As we caught up, they could still be heard thrashing away in the small canal. We quickly began the upstream survey (walking, pleasant, long legs, ho ho!). From the maps it looked as though we had around a kilometre or so to the edge of the limestone, but we quickly emerged at a sink after a slightly disappointing 600m of easy walking. We had linked “sinks” 3 and 4, although not in quite the manner we had expected. At least we had solved the mystery of the 2km concrete carry!
Heading back, we checked out the remaining question marks, including a climb up into a vast high level chamber above the sink. Daylight could be seen high in one corner and Sweeney made a bold free climb up a buttress and along an airy traverse near the roof. It was indeed the light from a fourth entrance, but Sweeney’s quip of “It’s going to be a bugger to survey that climb” was met with a unified chorus of “Oh no it isn’t!” and “Come down carefully – we’re a long way from home”.
We exited without incident, only to encounter a small reception committee from the local army base, whose premises we were invited to visit. The camp commander greeted us with a smile, an iron handshake and the sort of steely gaze that you hopednever to be on the wrong side of.When he got out his Standing Instructions, we realised that maybe our attendance at the camp was not merely a social call.
Several pots of tea and a couple of hours later, after some extended questioning of our translators and the donation of a roll or two of film, we were on our way back to That Khe. The experience reinforced our view that no matter how many bits of official documentation you can amass, on occasion it will not be enough. Straying into an area just a bit too close to a sensitive border can end up with heavy discussions with those charged with guarding the country’s boundaries. It is understandable and at these times we have found that being calm and patient is by far the best option.
In the final analysis, Bo Nhon accounted for over 3km of survey. It was a fine cave with some spectacular situations tucked away in a quiet backwater. The remote feel of the enclosed Ban Gi valley was only partially belied by the existence of satellite TV dishes on the rooftops of some of the wooden houses! Another story to be filed away amongst the many fond memories of the expedition.