Following the success of the ’88 expedition, Mulu Caves ’89 returned to the Park just 11 months later with five of the ’88 crew plus three new faces. Blackrock was to be the main focus of the expedition but further work awaited in the Ronnie’s Delight area of Clearwater where Deep Thought remained undescended.
In Blackrock Cave two significant leads had been left in ’88 when the expedition ran out of time. The northern end of the Firecracker River remained open and ongoing as did the Racer Series, a lead off Firecracker which appeared to be heading for an entrance which, frustratingly, had not been reached in ’88 owing to a lack of rope to climb a small pitch.
The expedition was based at Kuala Lutut to the west of Leopard Cave and on the Melinau River; just at the start the Headhunters’ trail. This provided a much better camp site as it benefited from endless hours of sunshine and a river in which to bathe; undoubtedly improving team morale. The team split into two parties one heading north towards Blackrock and the other south to the Snake Track entrance of Clearwater Cave.
Early forays to Blackrock revealed a new cave Metric Cave lying to the south of Imperial Cave to form the continuation of the marginal drainage.
In Clearwater the party once again camped at Scumring but on arrival at the bivy a large passage was spotted at the top of a climb on the wall opposite. A fairly easy scramble led to an ongoing passage which provided the main focus of the expedition. This passage, named the Snow Slopes, due to the deep powdery white swift guano which covered the floor, formed a crossover passage which provided access to the main strike controlled passages of Armistice. A total of 15 km of new passages were explored in this series. Ronnie’s Delight and Deep Thought were put on hold indeed abandoned in favour of easier pickings.
Armistice was explored both north and south and provided a connection down into a new section of the Clearwater River, Clearwater 5. This formed a tall, 30m wide passage in places with sheer walls and fast flowing water. It was explored upstream for 1km to a junction which led to a tall aven. Surveying later revealed that this was almost certainly the base of Deep Thought. High water conditions had made the exploration of the river passage extremely arduous and as the expedition was drawing to a close it was left wide-open and continuing northwards in the same impressive style. Downstream from the point of entry led quickly to a massive sump pool which is very close to the upstream Clearwater 4 sump. This had been dived by Martyn Farr in 1984 but the dive was abandoned when it plunged to a depth in excess of 30m with no sign of levelling out.
In Blackrock the two main leads were quickly tidied up. Northern Firecracker only revealed another 200m of passage, much to the frustration of the explorers. The lead closed down and climbs led upwards into a large calcited bouldery chamber with no way on. This chamber lies close to the cliff line. In the Racer Series the pitch was easily climbed and led to the expected entrance with two other small entrances located above this.
It had been clear that the known Blackrock passages were formed at base level and although many tall avens were seen disappearing into blackness determined attempts to gain entry to higher levels were thwarted. However, a side passage of Damocles Hall, in the south of the cave, provided the key. A series of steep and complicated ramps finally yielded and led into an apparently isolated higher series 90m above the lower levels. This series, Phoenix, was at the southern end of the cave and there appeared to be no way of heading northwards over the main parts of the cave. A deep shaft was descended which appeared to be aligned with Gnome Oxbow in Clearwater but calcite blocked all progress. The Phoenix Series was explored southwards to a chamber (Broken Hope Hall) with a powerful waterfall but with no apparent way on. The only lead which was left in this horizon was an awkward climb with a powerful draft descending, named Pete’s Peccadillo. Blackrock’s main upper levels were to remain hidden for a further fourteen years, the ’89 explorers could never have imagined the labyrinth of passages which lay above forming Whiterock Cave.
Towards the end of the expedition an entrance known to local guides was explored to the south of Cave of the Winds. This was named Simon’s Cave, later renamed Racer Cave and revealed 1.1km of low-level, large passages with avens which hinted that greater things may be found above.
The expedition carried out a dye tracing program to establish links with the newly discovered streamways in Blackrock. Dye was introduced into a large sink east of Camp 5 in the Melinau Gorge, this would repeat a test carried out in 1980 which proved a link between the gorge and Clearwater but on this occasion allowed Blackrock’s Black Magic River to be sampled. The tests were successful and dye was detected in Black Magic and in Clearwater 2 proving that Black Magic is on the line of drainage from the Gorge to Clearwater.
In total the expedition explored and surveyed 25 km of cave and increased the length of Clearwater to 75km.