At the start of the expedition, one of the major remaining “gaps” in the Phong Nha catchment area was the course of the water from the Hang En / Khe Rhy sink to the upstream end of Hang Thung. The latter was explored in 1994 and left at an upstream sump, whilst attempts in 2001 to bypass the boulder choke at the sink had resulted in lots of walking and jungle-bashing and not much cave.
Our aim in 2003 was to head for the area between the two known points and, in particular, to a cave called Nuoc Nit which had featured in dispatches from the last expedition. The name had been translated, as among other things, “Meeting of the Waters”, which sounded ideal for our purposes. The only problem was that knowing the area around Hang Thung and Hang En, we anticipated an arduous, leech-infested thrash to the entrance and prepared ourselves for the full jungle experience.
Our transport to the roadhead was the usual heavy duty construction lorry. This one was perhaps a little smaller than we felt was ideal, but since our part of the group was to be deposited around 1 hour up the road it promised to be bearable.
Three hours later, we are sat by the truck 20-odd kilometres up the Ho Chi Minh road, way past our drop off point, with a broken fan belt and no spare….by now we have become accustomed to such distractions in Vietnam! One of the new recruits even used the time constructively to get to know the porters better – by the time we set off again, he could barely stand, having consumed several bowls of a strange opaque liquid from a yellow plastic oil container (No names, but he’s a scientist from Oxford with the initials CJD!).
After dropping the Hang Dai Cao team at the head of the road, we returned almost back to Son Trach and then headed off up the newly constructed road towards the Hang En end of the massif. It was now clear we would not be getting as close as we thought to our objective today! As
dusk fell, we arrived at the army camp at the roadhead. “It will be fine” said Mr. Thach and only half in jest added “either they will let us stay or they will arrest us!”.
Fortunately, they let us stay and we prepared our dehydrated jungle rations in the camp kitchen. These, along with several litres of water, seemed to undo most of the damage the rice wine had done to Chris and we retired to our beds (wooden, army, covered) to ready ourselves for the rigours to come in the morning.
The rigours consisted of about a kilometre walk back down the road, followed by a quick bash through the jungle to a wide, dry streambed. Following this for a couple of kilometres, we gradually approached what looked to be a more caverniferous lump of limestone. The stream dropped down over a series of boulders and suddenly we had arrived. The entrance to Nuoc Nit, a 15m wide by 30m high gash in the base of the limestone with a stream gently gurgling off into the darkness. The latest version of the translation of the name was “Water Go In” – we figured we had better go in as well and the frustrations of the previous day quickly began to evaporate.
Whilst the porters set their fishing nets in the entrance pools, we began the survey. Martin, Woody and Paul measuring and noting, Chris scouting and Deb on international relations duty with the Vietnamese who accompanied us into the initial part of the cave. A short crawl just inside the entrance quickly gave access to a pleasant section of streamway with pools and gours which led up rightwards to another entrance in the cliff. We were far more interested in the downstream end and Woody was quickly impressed by the chamber into which we emerged following the gour dam section. The chamber continued for some way; in fact the chamber was a passage of the more traditional dimensions, i.e. at least 50m wide and 30m high. The expedition was now truly “Up and Running”. Deb volunteered to return to the army camp with the porters to bring down the rest of our camp gear (we had initially travelled light to check that there was something to carry our heavy loads for).
The main passage continued in fine style – a vast boulder and cobble floor interspersed with sandbanks and decorated with huge stal formations. The stream trickled insignificantly along under the classic arched roof of the Vietnamese river cave. After approximately 800m, a boulder collapse area made for more awkward going. At this point we noted a substantial stream inlet emerging from the left wall, but obviously followed the wide-open downstream route. With a more active flow, we now believed we were onto a winner and wondered if we would meet Hang Thung upstream or downstream of the sump. As always happens, such thoughts proved to be counter-productive as the roof began to lower and the water drained away at the foot of a wall of rock, which appeared across the passage. Overflows to left and right both ended in sumps and bold attempts by Chris to enter a possible roof tube by combined tactics failed. 1.2km in and we were facing disappointment.
Returning to the inlet area, a climb up the boulder collapse led into a high level branch which was followed towards the sound of the river. A sandy slope led down to the edge of a lake with the sound of rushing water beyond. Chris swam over in his underpants (good lad!) and returned with stories of a swim to the base of a cascade. Having no wetsuits at that stage, we tactically withdrew to the entrance just in time to meet Deb and the porters with the rest of the kit.
An evening trip added a further 600m of survey including the high level series around the entrance. As well as taking photos of the beautifully decorated gours and chambers of the “Stal Magicians’ Workshop”, we also committed the main passage to celluloid. Over the evening camp fire and (for some) a wee dram or two, we mused on the origin of the inlet. Could this be from Hang En? We doubted the flow was anything comparable to the Hang Thungriver, but it was very dry in Quang Binh…
The following day, armed with wetsuits, we returned to the inlet and began the survey. The lake led to a canyon, which could be traversed in part, but often necessitated swimming. It was named “Ribbit River” in honour of the noisy frogs that had bellowed throughout the night and thwarted our attempts to sleep (but several of which were quite tasty!). The cascade was climbed without too much trouble and we quickly rejoined the river in a deep canal. A few legs along this, we were confronted by a blank wall. The water welled up from a deep sump and no airspace could be detected. This was disappointing given our hopes for a link back into the main drainage system, but nevertheless it was an excellent cave in the true Vietnamese style.
Upon plotting the location and the survey of the cave on our maps back at base camp, it became apparent that the Nuoc Nit river is an independent water course, undoubtedly joining the Phong Nha system, but unlikely to be directly associated with known caves. In this respect, our attempts to fill the gap have only raised more questions. The origin of the Nuoc Nit inlet is still not known and the great imponderable of the fate of the Hang En / Khe Rhy river before it meets Hang Thung remains a mystery.