With the ‘93 recce providing sufficient leads to justify a full expedition the team headed off into the unknown and inhospitable terrain of the Hidden Valley dolines.
During October 1996 members of the Sarawak Forestry Department together with 8 British cave explorers visited the Hidden Valley area of the Gunung Mulu National Park in northern Sarawak. Seven new caves were discovered and a total of 10.5km of previously undiscovered cave passages were explored and surveyed in the deep dolines beyond the Hidden Valley gorge. The Expedition entered totally unexplored areas of the Park which, due to the inhospitable nature of the terrain, had never before been visited by man.
A camp was established near the ‘93 camp. Although this was of grander proportions it soon became a rather squalid and damp home. A cook house was erected adjacent to the stream but flood waters washed through this on a regular basis. Owing to the heavy rains experienced during the expedition the river beds which had proved such useful roads on the recce had become fast flowing rivers, best avoided.
At the lower end of the valley a large low-level entrance was discovered named Damocles Cave. This had been seen by Park guides during the ‘93 recce but not recorded. A large entrance led into a major passage which quickly choked. The only onwards route was downwards onto a series of pitches which resembled a classic Yorkshire pothole. A final 35m pitch led down into a horizontal continuation which headed wide open in a southerly direction. However, owing to the fact that this cave formed the main sink for the western end of the valley and that heavy rain was experienced on a daily basis it was considered prudent to leave it unexplored beyond this point.
Beyond Damocles Cave the ground rises up from the flood plain of the valley floor onto limestone terrain. This ground makes very difficult going with loose boulders, pinnacle karst, deep pits, dense forest and a series of deep dolines.
This inhospitable area was the key to the major discoveries of the expedition.
Above the first doline No Name Cave was found on the southen slopes. In the second doline Arch Cave had been noted as an open lead in ‘93. This was explored along a stremway in both directions and eventually connected to Yellow Viper’s Pit which the surface track passed and which dropped into the upstream section.
In the third and deepest doline Perseverance Cave was discovered in the west wall and on the opposite side of the same doline Bridge Cave was discovered within a collapse feature which contains a magnificent natural rock arch.
In the fourth Doline Cloud Cave was discovered, this contained a main passage of Deer Cave proportions.
Further minor entrances were seen in the surrounding area incuding a large calcited entrance high above the fourth doine which had been seen from the air and was named Helicopter Cave. Unfortunately attempts to gain acces to this were thwarted.
Towards the end of the expedition exploration down a deep bouldery ramp in Cloud Cave led to a connection with Cobra Cave in the Melinau Paku valley. This link establised the Cobra/Cloud System as the deepest cave in the Park.