AREA 33: Dong Van

DV1: Xa Lung 1

Development: 262 m
Denivelation: -178 m

The entrance of this cave is immediately beneath the road on the left side just before entering the village Xa Lung. There is another entrance on the right side. One goes down a steep slope and then into a doline which gives way to a beautiful and large pitch (P114). Descending this pitch, one lands
in a rather big chamber (25m in diameter) with a flat muddy bottom and a sump at the far left side. No way on could be found, although the dimensions of the site left us dreaming of a huge collector system.

DV2: Xa Lung 2

Development: 700m
Denivelation: -340m

Xa Lung 2 is situated at the left hand side of the road entering the village Xa Lung coming from the direction of Dong Van. The path passes first the entrance of Xa Lung 1 (left side) a few hundred meter further (right site) a depression in the fields gives way to a canyon. Following the canyon a first steep boulder slope is descended (R9). A short passage gives to a P21, it is a descent in a kind of a joint. At the bottom a larger room with some huge blocks is found. Day light enters the cave from above via a P35, which is descended two days later and called ‘the flying goat’ pitch. The reason of an unpleasant smell is found after a next step down: in a round room a rotting goat is found. At the opposite side of the room the top of a deep pitch is reached. The pitch, with a free hang of 44 m at the end, brings us to -120 m. At the bottom a lake can be avoided via a pendulum. The cave continues with small drops, followed by small lakes at the bottom. At the moment of the exploration no flowing water was present, but the clean walls suggest a huge discharge during rainy season. After a P20 the cave becomes more narrow and sportive. A nice meander gives to a P27, the passages are larger again. At the first real inlet a flowstone almost chokes the passage, but at the bottom the cave continues with a P23. When the passages (3 to 5 m wide) go up again a small window gives way to small drops: a P10, P11. Then the cave development changes completely. A horizontal muddy collector is reached. After about 120 m the ceiling comes down and a sump is reached, at a total depth of -340 m. The last pitch is almost exactly situated below the entrance. The plan of the cave shows that the passages turn below each other, resulting in a screwdriver like development.

DV3: Ma Le 1 and DV4: Ma Le 2

Development: 218 m (DV3) & 893 m (DV4)
Denivelation: -56 m (DV3) & 44 m (DV4)

Ma Le 1 and 2 constitute together the underground course of relatively important river. They are connected by a sump. The river disappears in a large porch at the bottom of a beautiful and deep valley below the village Ma Le. However the access to the underground course is through another big porch approximately 100 m to the right of the first one and some 30 m higher. Here a boulder slope and a short drop of 20 m at the right side allows one to join the river. The river can be followed for about 150 m through a nice gallery (7 x 4m) to a sump. According to local people, the sump can be dived free, but we didn’t give it a try since all the rubbish was not very inviting. Ma Le 2 is an entrance at the other side of the mountain and gives access to a continuation of the river. Upstream the river can be followed over approximately 800 meters before a sump is reached. This sump is supposed to be the one of Ma Le 1. The gallery leading towards this sump is large and really beautiful. It starts by two waterfalls of about 4 to 5 m which can be climbed either to the right or the left side. Then the gallery widens up and allows an easy walk along many beautifully decorated walls. Downstream the river can only be followed over a short distance. This part quickly ends in a sump between pebbles. The water of the Ma Le river reappears in fact a few hundred meters further in the same valley, but there is no entrance to be found here.

DV5: Tia Sang

Development: 1154 m
Denivelation: -107 m

In this area the water is flowing in many small rivers on top of the siltstone. When the water reaches the limestone it disappears in different sinkholes over more than one kilometer. Tia Sang cave is the only sinkhole which can be entered. It is situated at the contact between the limestone and the siltstone at the bottom of a deep depression and under a huge limestone wall. This active cave develops along a fault axis and is mainly directed south. It starts with some vertical passages. The river which is flowing down in different steps can be avoided with a horizontal traverse above the water. Descend approximately 7 m and swing away from the entrance over 3 m. A window opens at the right side. This window gives way to a dry seriesof small pits. Three natural anchor points can be used to descend to the foot of a small waterfall. A spit allows to descend another 12 m, a final spit allows to descend the last 4 m.
The underground river can be followed over approximately 300 m to a chamber in T-shape. To the left the cave turns back. The river flows to the right in a gallery of approximately 6 m high and 20 m wide. The right side of the gallery is a big mud slope. Soon the river can not be followed anymore.
This passage can be bypassed at the high right side, where a window high up the mud slope gives access to the continuation of the river. Stay high up the mud slope till an important inlet is met at the left side. At this point, slowly descend to the river. The river can then be followed over several hundreds of meters, the size of the gallery is at most times reduced to a few meters high and wide. Suddenly the gallery gives access to a gallery of big dimensions: 10 m high, 30 m wide. Several muddy inlets feed the river during rainy season. The river finally ends in a big sump lake: 20 m by 20 m. This sump is certainly worth to be dived. The water is supposed to feed the resurgences around Dong Van city.

DV7: Xa Xa Phin 2

Development: >200 m
Denivelation: -

During our visit obvious signs of earlier speleological investigations were found in the cave. We didn’t continue the survey as we expected to find the same results of the former speleological investigation. Until now no data about this cave are found.

DV8: Xa Xa Phin 1

Development: 191 m
Denivelation: -32 m

Old fossil cave, large room.

DV9: Hmong Castle

Development: 74 m
Denivelation: -29 m

The entrance of the cave is right next to the road. It is an old sinkhole, filled with blocks from road works. One can walk down to the bottom, where a few concretions are present and water is seeping in.

DV 10: Hang Ho

Development: 337 m
Denivelation: -14 m

One can follow the stream for about 300 m until reaching a sump. At several places the ceiling becomes very low. Lots of debris can be seen on the walls and ceiling from periods when the water level is higher. Close to the end of the cave is an inlet with more than half a meter of wet mud.