The entrance section of Tham Phra Wang Daeng is a huge collapse chamber with two entrances facing each other. A foot path crosses through the upper levels, passing a golden Buddha and a flat, painted rock symbolising a turtle. Two monk platforms are erected in the middle of the entrance chamber. On the opposite site, the path continues to the downstream entrance of the cave.
Descending the steep boulder pile in the entrance chamber, a small hole in the floor fixed with a cellar door gives access to the upstream section of the cave. Inside, the steep descent over huge boulders continues, finally dropping over a concrete stairway to the bottom of the first (entrance) boulder choke. Here the stream is reached. Downstream the water quickly disappears into the boulder choke, but it can be rejoined after a few hundred meters from the downstream entrance. Upstream, a huge gallery opens into the darkness, just waiting for exploration \dots.
Some gours damming the stream soon lead to the first swim. Here a steep climb to the left (as seen in downstream direction, as always in this report) is rewarded by a large Buddha statue, while an even steeper climb to the right over muddy flowstone, rigged by the local monks with a thick knot robe, leads to an upper dry gallery some 30 meters higher. Again, the passage is dominated by a golden Buddha statue. At the far end of the bypass, a slippery boulder pile leading down to the stream has to be negotiated, this time without the help of a handline. Thus, the bypass can be used to avoid the first swim. Back down at stream level, a large pool is found, which hosts an abundance of a still undetermined species of white cave fishes. Some of them are now examined in Bangkok.
From the first pool on, the passage obviously leaves the entrance area dominated by its huge boulder choked sections and gives way to several hours of walking, swimming and bouldering along the main streamway. The sizes of the gallery start with around 10 meters width and 5 meters height, but successively increase to a width of 25-30 meters and a height of 20-25 meters. Only few minor inlets are passed, all of them dry at this time of the year (April, the end of the dry season). Clearly, these inlets cannot account for any significant amount of water in the main streamway. After little over 2 km, a second huge collapse area is reached. The entire river passage is blocked by a huge boulder choke, giving access to a large, dry boulder room at roof level. Here a major fault zone is intersected by the cave, as a result the ceiling has collapsed with its overlying sandstone layers, burying the stream passage for approximately 100 meters. A tiny red string marking the best way through this unstable zone gives us a glimpse of the toughness of the monks, who explored the cave only with the help of candlelight.
After passing the second boulder choke, the active passage continues in a southerly direction. At a false junction, a dead end passage leads straight ahead, while the streamway makes an obvious easterly turn. The dimensions of the gallery become smaller again, with average passage sizes of 10x15 meters. The phreatic origin of the passage is more obvious here, with an elliptic tube in the upper part of the section and a meandering vadose streamway cutting into the lower parts. Twice, the streamway is almost entirely blocked by flowstone, and at a small cascade a basaltic dyke is intersected by the gallery. Roughly 3 km from the second boulder choke the passage enters a huge fault, leaving the ceiling some tens of meters higher. A sizeable, but at this time of the year dry inlet enters from the left. The rift passage, intersected by a bouldery section at an obvious bend, continues unsurveyed. Thus, the monk was right, and we have to come back.
The downstream section of Tham Phra Wang Daeng, though less long, is characterized by a sequence of small cascades.