This cave forms an important part of the Nguom Sap system. The previous section of cave, Nguom Tu (Death cave) resurges into an enclosed valley, which contains the village of Lung Cung. The local villagers were very surprised at our appearance in the usual brightly coloured wetsuits and caving kit. They informed us (via Mau our Vietnamese member) that the river from Nguom Tu did not enter another cave, but that the water went to China. As there is no surface river marked on the map and the valley is enclosed we can only presume that the water sinks, but there is no enterable cave. We did not have the opportunity to check this.
The villagers did inform us of a flood overflow cave in the valley called Nguom Cang and led us to the entrance. An obvious wet season sink, which looked as if it backed up in times of flood, Nguom Cang had a very strong cold draught, which could be, felt 30-40m away.
Surveying in over the muddy boulders and flood debris we soon reached a lake. This chest deep wade proved to be composed of half liquid mud and half freezing cold water (by Vietnam standards). After about 100m, a large mud bank was reached leading to a side passage. This dry passage led to another exit after about 100m. As both entrances were draughting out strongly it was obvious there was more to this cave.
More wading in mud and water led us to an area of collapse and flowstone. A large entrance (30mx30m) was seen entering on the left. The cave could be seen to continue with large gravel banks and small pools.
Returning the next day, we were disappointed to find that the large walking section was short-lived, and we were soon swimming in the cold water. The water temperature was about 15oC, which was too cold for 3mm wetsuits. The strong draught also meant that the brief moments out of the water were no warmer. About 1 K of cave was explored, mostly swimming. Two orthree gour dams were encountered, where you had to swim to the dam, climb over it and drop down a couple of metres to the next swim. As it was the dry season, no surface water was entering the cave. These dams held back large sections of ponded water, which consequently was much colder than the usual Vietnamese river cave.
Finally we emerged from a swim onto a gravel bank, and found 2-300m of dry gravel floored passage. After the previous kilometre of tall rift passage this section was very wide and lower-roofed. Passing some dried gour dams, we found the inevitable canal between flowstone banks.
Returning for the third trip into this cave we all wore life jackets, more for the hoped for insulation than buoyancy. Traversing the known section of cave we managed to keep reasonably warm, but once the surveying in cold swims began we soon cooled off.
The swims in the next part of cave, were generally shorter and interspersed with drier, muddy sections. After about 3-400m, we met an 8m climb down from the large dry passage into a 3m wide flowstone lined canal. More swimming followed in this well decorated passage. A short walking section led to a drop into a large lake. Sumped all around the left hand wall, this is possibly where the main stream enters the cave. The outflow from this pool is quite strong. The continuation although largely wading and walking was awkward due to underwater projections and sharp limestone flakes. Unlike the previous part of the cave there were several active sections with a fast flowing stream
The cave finally exited after a further 500m just above the valley floor. A limestone cliff could be seen opposite. After calculating the data, the exit was determined to be still just inside the Vietnamese border. The total length of Nguom Cang was 2,695m.