THE NGUOM SAP SYSTEM
The Nguom Sap system has now been explored for a total 13.7k. the system comprises 8 separate caves: Nguom Sap 5.4k; Nguom Lung Sam 2.7k; Nguom Cac Hao 1.0k,Hang En 208m,Nguom Nua 669m, Nguom Tu 419m, Nguom Cang 2.7k,Nguom Van 832m.
Exploration of the system began in 1997 with Nguom Sap. This is the highest sink, formed at the start of the limestone. Nguom Sap was surveyed for 2.2K in 1997 and extended in 1999 to 5.4K, with an exit in the Lung Sam valley. The stream is lost just inside the entrance, and can only be followed briefly before sumping. The majority of the cave is flood overflow or dry high level and is extremely well decorated.
After the conclusion of Nguom Sap the team crossed the col into the next valley and were able to explore Nguom Lung Sam. In this cave the river can be followed for the majority of the 2.7K, although there is some high level development. The cave ends in a sump, but there is an exit 2-300m before, known to the locals as Nguom Nuoc.
The team did not return to Ha Lang district until 2003, when the continuation of this system was one of the main objectives. This was made easier as a road was being constructed to the valley of Lung Sum. The local villagers were happy to show us several entrances in their enclosed valley.
Heading upstream, we were first shown a high level dry cave known as Cac Hao. This cave is extremely well decorated, and so far has suffered little damage. Ending in a calcite choke, there was no obvious way on, although the draught remained.
A short remnant of enormous cave called Hang En was traversed. Dropping down into the valley beyond brought us to the other entrance to Nguom Lung Sam. Finally we explored the main resurgence, which is the continuation of Lung Sam beyond the sump reached in 1999. A fine section of stream cave, which ended in a large terminal sump after 750m.
Heading downstream led to the sink named Nguom Tu. Although only 419mlong, the cave was full of deep water and could only be negotiated by swimming or inflated inner tube.
We emerged into another enclosed valley, with a small hamlet called Lung Cung. Initially very wary the locals soon became friendly after a discussion with Mau, our Vietnamese caver. They told us there was no cave where the main stream sank, and although we did not get a chance to confirm this we presume they meant no accessible entrance. Instead they showed us the flood overflow sink called Nguom Cang. Although the entrance did not look too inviting (large boulders, log jams and mud everywhere), the icy draught could be felt some 20m away.
Surveying over the boulders we soon reached the start of what was to be a very cold section of exploration. Nguom Cang was surveyed for 2.7k mostly by swimming. It was well decorated in places with large gour dams. Lower down, probably in a very large pool the main water enters the cave. Several hundred metres later the cave exits into another enclosed valley.
Due to the cold nature of this cave, an overland route was sought and found to this valley. The stream flows across the valley for about half a kilometre before sinking again in Nguom Van. After only a couple of hundred metres, with lots of swimming the passage deteriorates into a series of rifts and cross-joints, worn into very sharp edges. A 10m climb up led into a very large chamber or passage.
At the other side of the chamber is a pitch leading undoubtedly back to the stream. A high entrance to this chamber is more or less on the boundary with China. The end of the expedition prevented any further exploration. Some dry entrances in the Lung Sum valley also remain unchecked.