AREA 34: Pho Bang

PB1: Hang Ong

Development: 1523 m
Denivelation: -341 m

Hang Ong (Bee Cave) is a huge porch (more than 50 m wide, 20 m high) slightly above the valley bottom which can easily be seen on the right, across the valley from the new road going to Pho Bang. Giant blocks are scattered along the floor, which inclines steeply towards the south. To the east lies the first way on (described and surveyed separately). Down, a small stream flows along the southern wall into a narrowing gallery, still some 8 m wide, filled with large boulders and going down steeply. One needs to find this way through the boulders twice before arriving on top of the first pitch, P8. A horizontal gallery is followed by a descent trough boulders after which the gallery becomes more and more cave-like and meandering. A 6 m descent along sticky sharp-weathered
rock, followed by a small window-like passage brings you to a small chamber where the heading of the cave changes 180°. A major inlet gives into this chamber, where one can see a section through an ancient barrier of pebble deposits, a phenomenon that is observed at several other locations in this cave. An easy, horizontal man-wide passage starts from here and after a 3 m step gives onto a beautiful fault which is followed over 60 m to end up in a wide chamber where the streamlet reappears. Exploration stopped here on the first day at a depth of 170 m. A climb down and a 3m step leads into the river, flowing through a high but narrow fault-like passage. A 4 m cascade, which required particular rigging in order to remain dry, gives into a basin followed by a 3 m step. A 6m
pitch brings you to the bottom of a beautiful chamber with a shallow basin, fed by a 3 m cascade. From here the cave starts heading south-west in a wide meander through which the river is running constantly. A 2 m cascade lies just behind a polished block jammed in the passage and gives into a basin. Around the corner lies a deep and wide basin with a dry part higher up on the right side, giving onto a 6 m pitch along a cascade. The canyon goes on and gives into a wider, silent area, the ‘picture gallery’ where a lot of time was spent taking photographs on the second day of the exploration. A deep basin is followed by an easy passage ending on a 4m cascade at -250 m. The aspect of the cave changes at a steeply inclined passage with running water underneath two natural bridges. This passage is followed by a 6 m cascade giving into a deep and long basin, where one can hardly stay out of the water. The basin is followed by a narrow passage giving into a little wet chamber with another 5 m cascade. A wider and dry passage follows with a few formations, a rare phenomenon in this cave. Then the meandering wet canyon passage resumes, with 5 to 10 cm large calcite crystals on the wall, giving onto a charming 4 m cascade. A dry canyon with sandy bottom departs at the top level of the cascade which was explored for over 50 m in a straight line without reaching the end. Down the cascade, during the fourth day of exploration, the wet canyon continues over a difficult 2 m step to arrive in a wide and quiet place, contrasting to the noisy canyon. At -300 m, the passage gives on top of a long slope with the ceiling running parallel at a height of some 80 cm, along which the water runs down. This bizarre phenomenon is probably shaped by the water that washed away one layer in between the inclined strata and is still continuing its sawing action. Due to
the slope’s angle and the low ceiling, a funny but very efficient way to move is spinning for some 70 m till ‘normal’ passage is found again at the far end’s bottom. Here the ceiling becomes gradually 40 higher and on crawls in between large blocks in a dry gallery. Water is found back on the left when going down. A last 4 m pitch was descended using improvised techniques. Here a flat part with a shallow basin gives onto pitch of an estimated 5 m which was not descended due to lack of rope. A bolt has been put in place for the next explorers. We’re close to -350 m deep and it seems to go on for a while. Although very little tackle (5 bags) is required to rig the cave and the deepest single pitch being just 8m deep, the cave is quite sporting; it’s a long way to the end and one needs to climb up and down blocks and small steps constantly.

PB2: Dong Nguyet

Development: 1143m
Denivelation: -78 m

The cave is situated in a blind valley close to the Chinese border, and has been a touristic cave during the French period. A metal ladder to the entrance, situated about 15m high in the rock face, is a remnant of this. The entrance lowers down into a huge chamber full of blocks. Following the right wall, first passing a nice dead-ending passage, one enters a wide passage and soon enters the only active part of the cave with some pitches, flowstone and sinter pools. Climbing over several heaps of blocks, one can follow this "corridor" with high ceiling for about 200 m. Returning to the big entrance chamber, one passes another, 50 m long, passage on the right. In the chamber, we follow the right hand wall again, coming to another big passageway, which splits into two after about 100 m. The right-hand gallery is large and becomes a little muddy at the end; the left-hand gallery becomes a freatic passage, low and narrow. Again returning to the big chamber and following the wall on the right, another passage is entered with some beautiful, fossil calcite pillars, thus named the Greek Temple. One can leave the cave there through a second smaller entrance. It could be possible to make the cave touristic again, although the visitors will have to be impressed by the mere hugeness of the chamber, as there are not many calcite pretties except for the beautiful Greek Temple.