The successes of the ’78 and ’80 expeditions had established Mulu’s reputation as the place to discover spectacular new cave and there was huge interest in a return trip.
This time the expedition split into two distinct teams. One, led by Ben Lyon, was based at Camp 5 and concentrated its activities on Gunung Benarat, whilst the other, led by Andy Eavis, focused on southern Gunung Api, operating mostly from a camp in the Melinau Paku Valley.
One point of cross-over came when the two groups joined forces to support Martin Farr in his attempt to dive Clearwater’s upstream sump. This was successful and Martin explored the vast canyon of Clearwater III in his wetsocks before returning to his support team, shivering on a mudbank, where he surfaced and nonchalantly pointed out that the cave was flooding. Fortunately a rapid exit was safely accomplished.
The discovery of Clearwater III placed tremendous pressure on the Gunung Api team to locate a surface entrance to this fantastic passage, a feat accomplished by Nick Airey. The entrance was an uninviting hole down through muddy boulders but it led into Clearwater and over the next few days a connection was made at high level with the main cave, opening up a number of leads to easy access and by the end of the expedition, Clearwater was another 14km longer. The Paku camp yielded other successes, too Drunken Forest Cave, Cobra Cave and the superb Lagan’s Cave which cut its way right through the southern tip of Gunung Api. In the high levels of Clearwater an entrance led to another isolated cave Nilong’s Cave which remains one of the highest caves in Api. A helicopter reconnaisance of the Melinau Gorge revealed a large entrance high on the slopes of Api to the southeast of Camp 5, this was Canopy Cave which, owing to massive sediment banks which block its entrance, was not explored.
The Benarat Team were equally successful. Both Benarat Caverns and Sakai’s Cave were extended further and an epic climb by Martin Farr and Tim Lyons gained the huge entrance to Tiger Cave, high in the cliffs overlooking Camp 5. Three more smallish caves were located on the western side of the mountain David’s Cave, Deception Cave and Menagerie Cave and following a helicopter reconnaisance an epic of track cutting reached a massive doline containing Gawai Cave, a short remenant of a once much larger system. But the big find for this team was Cobweb Cave a huge entrance hidden in the green western flank of Benarat and, inside, a highly complex phreatic maze which by the end of the trip totalled 15km of passage, with lots of leads for the inevitable return trip.
The combined efforts of the two teams in 1984 resulted in a further 54.6km of passage being discovered and surveyed, bringing Mulu’s total to 154.8km. But the expedition marked the ending of a phase of exploration – the next series of trips would be smaller but no less successful.