TT1 Kha Pua

Three kilometres to the North of the village of Lang Vua, after a short but heavy trekking, we reached the end of the world: a long rift, where we descended almost vertically for 150m. The descent into the valley is very difficult and slippery, one goes down using hanging tree roots and there is many rockfall.

Once we reached the valley, we followed the now dry riverbed with pebbles of over 50cm in diameter, where lots of water should pass during the rainy season. The entrance porch of the cave is 20m wide and 30m high. A huge gallery and a river were followed up to a sump. On the right, there is a small current leading to another sump. On the left side of the big gallery however, a 8m step can be climbed, where a gallery of the same dimensions can be followed. There’s a lot of draft in this gallery, and wind erosion phenomena can be observed. After a while, the second entrance was seen, a porch with the same dimensions, giving into another valley. We named it the ‘secret’ valley, because there’s no other way to reach this valley than through the cave.

In the secret valley, an underground river comes to the surface. This river wasn’t followed as we had no wetsuits. From the second gallery, we could hear this river on the other side of the slope. It will be interesting to go back and explore this ‘hidden’ river: the river flows towards the secret valley and into the sump, but we didn’t look for the place where the underground river comes from.

TT3 Trung Du

The sinkhole, a boulder slope beneath the hill, is located at the end of the valley, near the village of Trung Du. Two rivers (only one on the map) disappear here.

There are several entrances in this boulder choke, we went in through a narrow fissure close to the smallest river. A flattener (where we encountered a breeding duck, which was later on cooked by the locals) gives into a small room where one can climb down between boulders. Here the cave widens and gets higher. The ceiling is a bedding plane, which dips down about 35° under which the cave developed. Here and there this roof almost touches the floor and narrow passages are formed. Where there's a waterflow, the bottom is covered with a slippery organic layer. After a wide basin, a narrow passage gives to a P4. Here lies the access to a fossil part, consisting out of steep mud-covered passages (not surveyed).  Down the pitch the water disappears in a too narrow passage, covered with pebbles.