Whiterock Cave was discovered in 2003 when two Blackrock ‘veterans’ ventured southwards from Camp 5 to investigate the foot-slopes of Gunung Api, between the Gorge and Blackrock’s Racer entrance.

On the surface, not far from the northern end of Blackrock, a strong draft was noticed blowing down the slope. This revealed a 7m entrance shaft which led into a large, well decorated chamber with stalactite curtains, gour pools and stalagmite bosses. Subsequent exploration that year revealed three tall, well formed, strike-controlled passages stacked on top of each other. These were named ‘Ah Disto’, ‘Pensioner’s Paradise’ and ‘Zebra Passage’. Two large ramps were found and although these were not climbed in 2003, they formed the main focus of the subsequent expedition.

At the start of that trip, in 2005, the team anticipated that it would only take a couple of days to mop up all the leads in the cave, as it would soon connect with Blackrock. Fortunately this was far from the truth and it soon became apparent that Whiterock was one of the most significant caves in Mulu, holding the key to the continued exploration of Clearwater and the northern end of Gunung Api.

It had been thought that Blackrock was the dominant cave in the north of the mountain and that Whiterock would quickly break into known passages. This prediction was quickly proved wrong as the cave soon crossed over Blackrock without a connection. In fact, although the explorers didn’t know it at the time, they were 80m above Blackrock’s Firecracker passage.

Climbing the main ramp lead to a massive strike-controlled passage, ‘Up and Running,’ which headed off both north and south with links to a higher level, more ramps and more enormous leads. Back over the top of the ramp, a short passage to the west quickly led to the surface at the so-called ‘Midnight Entrance’. This is now used as the main access to the cave because it bypasses the ramps and allows access to the upper series without the need for climbing aids.

The cave took its name from a large white cliff, which cuts across the strike and forms a significant surface feature in the area. Its presence has influenced the development of many of the passages at the north of the cave. As they approach the cliff the passages become blocked by sediments, indicating that this area has been inundated by massive flooding in recent geological times. Wherever the explorers looked in 2005, on all horizons, they were stopped just short of the cliff line. As this point is 2.5km away from the Melinau Gorge they knew that there was great potential for further advances to the north. They also knew that to achieve these extensions it would be necessary to go deeper (eastwards) into the mountain to avoid the line of the cliff.

From Up and Running, large well decorated passages lead off to the east; these link into ‘Daydream Believer’, another massive strike-controlled passage on a parallel bedding, which forms the main route south. This passage is typical of Mulu ­ huge and very single-minded in its direction. From its northern end it runs 3 km due south and its furthest reaches are five hours from the entrance, testifying to the remoteness of this part of the system.

On a bend in the passage, a small ramp was seen heading downwards to the west. To the delight of the explorers, this broke out into the roof of Firecracker, ninety five metres below, making a connection with Blackrock and confirming Whiterock as a component of the vast Clearwater System. It is now clear that Daydream Believer is formed on the same bedding as Firecracker and forms the elusive upper levels, the possible existence of which had tantalised the explorers of Blackrock.

At the southern end of Daydream Believer is a massive boulder choke, ‘The Middle Order Collapse’, which appeared to be the end of exploration. However, a way on was quickly found which took the explorers to the galleries of ‘Insomnia’, ‘Highland’ and ‘Lowland’. About 1.5km from the Middle Order Collapse, they noticed a draught and followed up through boulders to emerge in an enormous intimidating black void. A subsequent survey revealed this space, ‘Api Chamber’, to be one of the world’s largest at 300m across with an estimated height of around 100m. Its floor is strewn with huge boulders, which make progress across it feel like a mountaineering expedition! At the southern side of the chamber are masses of fallen boulders and a way on here is possible. However, serious exploration has not yet taken place in this area owing to the remoteness of the site and higher priority, easier leads to the north. Undoubtedly this is a significant area for exploration as it could reveal high level connections with Clearwater, which lies only 815m to the south.

At the northern end of Api Chamber a route down through boulders led to a small pitch into the head of a massive ramp, which headed downwards at 43 degrees. This proved to be a second link to Blackrock and broke out at the small hole in the roof at head of the Eagles’ Ramp ­ a hole that had been noted in 1988.

During the exploration of Daydream Believer two major leads were found which head north, ‘Ancestors’ and the ‘Northern Line’. Both of these passages were deep into the mountain and had the potential to bypass the white cliff and head towards the Melinau Gorge; they were to form the main focus of the 2007 expedition.

As predicted, the Northern Line became the link to the Melinau Gorge. However, to the extreme frustration of the explorers it terminated in calcite and boulders only 373m from Camp 5. Reaching these northern limits is a major undertaking as the area contains masses of fallen boulders, pits and climbs which make progress extremely arduous. Beautiful gour pools decorate the chambers at the northern end - one metre high calcite dams holding back crystal clear water.

In true Mulu style another passage was discovered, 60m above the Northern Line and following the same bed, only to end 363m from Camp 5, also in calcite and boulders with no way out. Both of these passages must be very close to daylight.

In the heart of the cave various link passages were discovered which connect some of the large trunk routes and considerably reduce the time taken to reach the northern end of the system.

Surveying has shown that Whiterock/Blackrock is formed on three distinct horizons. The lower level is that of Firecracker and Rudang Gallery, with Daydream Believer on the same bed ninety five metres above. A further ninety metres above this lies ‘Bigness South’ which connects through to Api Chamber and ‘Janet’s Way’. Tantalising ramps lead up from this level, suggesting that even higher passages exist.

Whiterock is a truly amazing cave. At a total surveyed length of 42.9km it ranks as one of the most remarkable caves in Mulu. Its discovery was only expected to fill in a small blank area of G.Api but it has proven to be an extremely complex, multilayered cave which forms the upper levels of Blackrock and has pushed northwards to take Clearwater almost to the Melinau Gorge. At the end of each Whiterock expedition there have been more leads than at the start and 2007 was no exception! It is certain that the northern end of G.Api has much more to reveal, perhaps an exit into the Melinau Gorge with a potential through trip all the way to Cave of the Winds, 10.7km to the south-west.

The story continues.