Borneo – The Last Frontier…

03 October 2022

“Pushing through vast chambers and deep sumps, the lights of a million eyes would reflect back at us…”

By Monty Halls – expedition leader & television presenter

I type this particular missive from an aircraft high over Europe, thundering towards Heathrow. I’m several thousand miles, four films, and three meals into the flight, and at last have given up watching bad television and am taking the chance to reflect on what has been an insane few months of relentless travel.

To summarise, this year has seen projects and expeditions in Guernsey, Guyana, Snowdonia, Malta, the Slate Islands, Cape Wrath and – this latest trip – Borneo. Only the Monach Islands and Venezuela remain, then I can return my gently smoking boots to the rack just inside the front door, sink into the deep cushions of the sofa, and stare out of the window with eyes wide and hair awry.

A generation of nomads

We all travel nowadays, to varying degrees and with varying motivations – moving from place to place features strongly for all of us. We have become a generation of nomads, eternal Bedouin, constantly in motion, whether that be by car, train, plane or boat. But the purest form of travel remains on foot, and the best places are those to which we walk, cheeks ruddy and thighs aching. Borneo is such a place, and on this trip we explored deep into its emerald heart. This may be a cliche of travel, well worn and oft repeated, but on those muddy trails, on the high limestone walls, and in the deep caves, I also discovered a great deal about myself and my traveling companions. This, after all is said and done, is the essence of any real journey.

The Borneo project was a three week expedition in the company of the splendid Leo Houlding to go far underground into the Mulu cave system, and then to climb high up sheer cliffs topped with a green fringe of unexplored rainforest in the Melinau Gorge. We were very lucky to be surrounded by an extraordinary group of film-makers and local guides throughout, a highly functional team that worked together to strike into new places and seek out new landscapes.

Borneo – one of the last great frontiers on the planet

Borneo is the third largest island on earth, and remains one of the most evocative names for anyone raised on tales of jungles and exploration. The Mulu nature reserve is in the north west, a vast sprawling network of rivers, limestone mountains, and deep caves. The latter represents truly one of the last great frontiers on the planet, with the limits of exploration set by the constraints of human endurance and expedition logistics. Depending on who you talk to, it’s estimated that only twenty to thirty percent of all caves on earth have been explored, leaving many echoing caverns throughout the world still to be discovered. Many hundreds of miles of deep caves have been mapped in Mulu, and yet teams have had to turn back again and again, exhausted and spent, as the cave network carries on into the darkness before them.

We entered the system with the aim of locating a deep sinkhole called The Secret Garden. Here Leo – the climbing team leader – would scale the friable walls and emerge into the outside world to take a GPS reading, allowing a whole new series of calculations from this new fixed point in the cave system. I would sample the wildlife en route, photographing and recording the extraordinary creatures that live in perpetual darkness, and those that visit from the outside world to make forays into the cave system for refuge or for food.

Four days underground in ‘The Secret Garden’

I have worked in many demanding environments on previous expeditions but – certainly in wear and tear in equipment terms – the Mulu cave system is a class apart. We would be spending four days in the cave, quickly leaving the tourist routes as we trekked deeper into the darkness. The heat was oppressive, the ground slippery underfoot, and the implications of an injury as minor as a turned ankle truly horrendous. Down there in the gloom you are truly on your own, and the only way out is to be carried on the shoulders of your team mates through a series of squeezes and overhangs, over rubble and stalagmite, all in complete darkness and over the course of several days.

But what lies in the cave system for us biologists? Surely it is a stygian, fetid place, devoid of life, far from the sun and the forest that seems to sustain all else in Borneo? The answer to this question can be heard as you enter the first cave, the deafening clamour overhead that tells of an ecosystem bustling and heaving with life.

Making their home in the caves are bats and swifts, countless millions, creating in turn a whole new web of life with their guano. There are four species of swift alone, and twelve of bats. It is not the diversity that suprises though, it is the sheer abundance. At the entrance to the caves, and in the case of the swifts many kilometres deep within them too, are vast flocks of dark bodies twisting and fluttering in the darkness. I cannot remember a place where life is so concentrated in a single place, where scuttling, clicking, whirring, bustling biology assaults you at every dark turn.

Wildlife in the caves

We were only an hour into the first cave when I saw my first cave racer, sitting motionless in the darkness, a coil of reptilian ebony atop a stalagmite. This snake species is uniquely adapted to life in the darkness, picking up the echo location clicks of the bats and swifts as they hurtle past. The racer strikes again and again into the pitch blackness, trying to snare a scrap of life that is hurtling past like a dark bullet. More often than not it fails, but one meal every few days suffices for an animal that sits with cold-blooded patience for most of its life.

Pushing through vast chambers and deep sumps, the lights of a million eyes would reflect back at us. These are huntsman spiders, the largest of which has a leg span of 30 cm, and has been known to take small swifts and roosting bats. These would be our sleeping companions as we bedded down on the cave floor for night after night. They share nooks and crannies with giant crickets, with millipedes, and with cockroaches. And most feared of all by our local guides, the giant centipede, a ludicrously venomous nightmare of an insect that grows to 20 cm in length, sports large mandibles, and is famed for it’s ferocity and what one guide book poetically describes as its “poor attitude”.

And what of the Secret Garden? Guided by caving legend Andy Eavis and his right hand man Dave – himself a lean, angular figure, a cave racer indeed – the team emerged blinking into the light of the sinkhole after two days of cave travel.

“Welcome to the Secret Garden,” said Andy with a smile, “more people have stood on the moon than where you’re standing right now.”

Below the circular entrance to the sinkhole far overhead, the ground had been eroded by several millennia of rain. Limestone has been cruelly moulded and honed into a series of razor sharp edges, so we tip-toed through a cauldron of daggers to our camp on the far side of the vast amphitheater of the cavern.

Establishing camp in this lost world

Once we had established camp, Leo set out on the climb, a remarkable test of nerve and skill taking place miles into a remote cave system, far from rescue and beyond help. I watched him inch up the loose limestone of the wall, before turning away to head back into the gloom to look for evidence of the creatures that inhabit this lost world.

What we found was mind boggling, and included the prints of a cat, deep in the gloom, positioned in a bottleneck in one of the tunnels, next to a pile of swift feathers and half consumed corpses. The prints looked large enough to be those of a clouded leopard, a creature who’s name alone evoked thoughts of poise, mystery and beauty. But what was it doing here, deep in a cave system where the only way in was many kilometres away, and even the most agile of cats could not climb in or out? It’s a riddle we could not solve, the answer lost in the darkness.

Cave guide Dave took us into one of the more remote passages of the system, and allowed me to help him map a short section.

Standing where no man has ever been before

“There we go, fella,” he said with a beaming grin, head torch bobbling in the gloom, “you’re now standing where no man has ever been before. Pretty good feeling, eh?”

And here was a constant theme through our expedition – that caving represents the last great frontier of exploration, man’s final journey and the last horizon. We emerged from the system four days later exhausted, muddy, but elated – we’d walked, crawled and scambled into another world. Perhaps for true exploration, to see the last horizons left to us in terrestrial world, you need resolve, a good pair of boots, and a vast cave.

Photo: gualtiero boffi/Shutterstock.com
Photo: sunshineinlove/Shutterstock.com


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