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The Biggest Black Hole

The Biggest Black Hole

Apr 2018

Words Matthew Holt, pics Matthew Holt and Fiona McIntosh

Our headlamps cast tiny pinpricks of light on the chamber walls, while all around was darkness. A gigantic stalactite – over 30m long and several million years old – cascaded down from the ceiling, like lava caught in mid-flow.

“The Dog’s Bollocks”, announced Watto proudly, puncturing the silence with his flat Yorkshire vowels that sounded straight from a Monty Python sketch. Strangely, the incongruous commentary made our expedition through Son Doong even more memorable.

Several days earlier, Fiona and I had arrived in Son Trach, on the edge of the Annemite Mountains. It was classic Vietnamese scenery; finger-shaped peaks, slowly meandering brown rivers, water buffalo submerged in muddy pools and women in wok-shaped straw hats bent double in paddy fields. Add a guest house with a poolside bar and it was very pleasant, but we hadn’t come here to lounge about at ground level.

With underground rivers boring through the karst terrain, the Phong Nha-Ke Bang National Park is a honeycomb of subterranean grottos, including the world’s biggest cave, Hang Son Doong. First explored in 2009, “Mountain River Cave” was only opened to the public in 2013, with fewer people having visited it than have stood atop Everest.

Exploring Hang En, above camp.

We were staying at Chay Lap Farmstay, owned by the Vietnamese company Oxalis, which has the exclusive permit to run trips through Son Doong. We met our team at the safety briefing. In addition to Fiona and me, there were eight other punters, including a philosophical Romanian professor, a brash Vietnamese stockbroker and a mysterious, sexagenarian Czech, who had visited this region in the 1960s during the Vietnam War. There wasn’t much spelunking experience between us – but, beside a modicum of fitness, the primary qualifications were having a spare US$3000 (R41 000) and fast keyboard fingers, since Son Doong trips sell out within hours of being posted, a year in advance.

Our lead guide was Ian “Watto” Watson, a blunt but soft-hearted Yorkshire man, who’d potholed around the globe, despite looking more suited to fairground boxing. Our retinue also included six assistant guides, two cooks, 20 porters and a government ranger: while we faced several challenges on the trip, malnutrition and a lack of attention weren’t amongst them.

The next morning, our party slithered down a muddy trail into a deep gorge; the lush jungle alive with clouds of giant butterflies, with wings like book pages. There used to be elephants and tigers too, but the main predator now was leeches, as we quickly discovered when tiny ticks stuck to our arms like Velcro, inflating within seconds to the size of fat slugs.

On the boss in Look Out For Dinosaurs.

Reaching the valley floor, we followed the Rao Thuong River, criss-crossing from bank to bank. On the first crossing, we gamely attempted to boulder hop across; the second time, we faffed around, taking off boots; and the next dozen times, we just ploughed through, resigned to wet feet. We hiked for three hours on the first day, which was quite enough. Though we’d been in the country for several days, we still found the humidity draining.

We spent the first night in another cave, Hang-En, which was also in the speleological premier league. A modest head-high cleft opened up to reveal a huge chamber, replete with an underground lake, which served as our swimming pool. With candles flickering on the scalloped cave walls, and a dinner menu comprising papaya salad, coriander chicken, chilli beef and pork in peanut sauce, it felt more like an exclusive eco-hotel than a cave.

We were even serenaded by thousands of swifts, returning to their nests at dusk, darting and diving above our heads. The magic began to fade, however, when we noticed splattering around us, forcing us inside our tents to shelter from the bombardment of droppings. And when we packed up the next morning, scores of baby swifts hopped pitifully about, dragging broken wings, having fallen from their nests high above.

Leaving Hang-En, we re-joined the Rao Thuong valley for a couple of kilometres and half a dozen more river crossings. The entrance to Son Doong was discreet and slightly menacing; a gash in the cliff plunging straight down into the underworld, with subterranean rapids roaring below.

Heading up to the Garden of Edam.

It was discovered in 1990 by local hunter Ho Khanh, who, remembering tales of a mountain dragon, thought better of entering. Several years later, he divulged his discovery to some British cavers exploring the region – but, having whetted their appetite, tantalisingly couldn’t find it again till 2008.

The following year, a team of six British cavers, primarily from Yorkshire, came out. Their journey to the cave was adventure enough, with snakes, poisonous spiders, giant centipedes, blood-sucking leeches and unexploded bombs from the Vietnam War. Despite several exotic injuries, however, they made it in and – over the next few years – progressively penetrated the cave, with several of the pioneers now working as lead guides for Oxalis.

While only 8km in length, we spent two days traversing Son Doong, staying at two campsites en route. There were several technical sections, including rock bands and river crossings, where it was necessary to set up belays and safety lines. But the primary reason for our leisurely pace was the incredible subterranean architecture.

There were giant stalagmites and stalactites over 70m tall; tiers of crystal clear rimstone gours, like infinity pools; and trays of cave pearls, the size of cricket balls. Taking photos of them was like shooting a Hollywood movie, requiring precisely positioned tripods, perfectly still models, carefully choreographed flash lighting and multiple retakes – and we spent several hours capturing blurred images of features such as the Dog’s Bollocks and Hand of Dog. (First mapped by the pioneering British team, the cave’s prominent landmarks typically had irreverent names, which were sometimes witty puns on features in other famous caves, or other times plain rude.)

Cave pearls.

At its most spacious, Son Doong measures over 200m high by 150m wide, outsizing Borneo’s Deer Cave as the world’s largest cavern. Inside, however, it was impossible to appreciate the scale, our headlamps making virtually no impression in the voluminous chamber. Comparisons of how many Boeing 747s or Saint Paul’s Cathedrals theoretically fit inside just don’t capture the sensation of being surrounded by so much dark, empty space. When I walked away from the group and turned off my torch, it was like being swallowed by a black hole.

While classified as a single, uninterrupted chamber, Son Doong is punctuated by two large dolines – or sinkholes – where the cavern’s ceiling has collapsed, leaving large mounds of debris on the floor and gaping holes in the roof.

The first doline was named “Look out for Dinosaurs” and, scrambling up the scree towards the light, I half-expected to see pterodactyls wheeling overhead. We emerged in a circular depression surrounded by 150m high cliffs, with a large calcite pedestal – or stal boss – illuminated in a shaft of morning sunlight. The primordial atmosphere was snapped when we found shrapnel from a bomb casement dropped by an American B-52, with Phong Nha-Ke Bang on the route used by the Vietcong to ferry troops and provisions to the frontline. After posing for photos on the stal boss, we clambered down the opposite scree slope back into darkness.

The Dog's Bollocks stalactite.

The second doline, a few kilometres on, was called “the Garden of Edam” (after the Garden of Eden in Deer Cave, which takes itself more seriously). Sunshine and rain entering through the hole in the roof had allowed a small jungle of luxuriant vegetation to thrive, and we had to barge through a tangle of trees and creepers.

Having camped just beyond the Garden of Edam, the following morning we came to an underground lake, 600m in length and sufficiently wide that our headlamps died in the void. Four small rowboats had been stored in the cave and we took turns paddling across, two to a boat, with a porter laboriously shuttling them back. The flat-bottomed, plastic vessels were as stable as wake boards, and it took some concentration not to flip. With just our faltering headlamps to guide us, it felt like we were crossing the River Styx – but my morbid musings were interrupted by a loud splash, when the boat containing the Romanian professor and Vietnamese stockbroker capsized.

Reaching the far side of the chamber, we moored and cautiously disembarked on to an aluminium ladder, which led on to a caramel-coloured cliff.  Known as “the Great Wall of Vietnam,” this 90m high calcite band had repelled the first expedition and, till only recently, marked the end-point for commercial trips, which then retraced their steps. Craning my neck, I could make out the headlamps of Watto and an assistant guide, perched on a ledge high above. Though the damp rock offered surprisingly good traction, I was grateful for the belay and fully appreciated the commitment of the first party to climb it, in the dark, not knowing where it led.

Admiring stalagmites in Son Doong.

As it was, from the top of the wall, a bell-shaped ray of light led to an exit in the flank of the mountain, from where some fixed ladders and ropes took us down to the valley floor. A couple of hours later, we emerged from the jungle onto a tar road, to find our bus already waiting.

That evening, back at Chay Lap Farmstay, we celebrated with hot showers, fresh clothes and champagne. After all, life’s successes are fleeting. Son Doong is only the biggest known cave in the world for now, until someone discovers a bigger one – which might be tomorrow.

Fact File

Entry to Hang Son Doong is tightly restricted. Oxalis, the sole licensed operator, runs weekly trips between February and August. The 4-day trip costs US$3000 and is limited to 10 clients. It requires a moderate level of fitness, but no prior caving experience. 

Oxalis Adventure Tours | Jungle & Cave Trekking Tours
Oxalis provides high quality cave and jungle adventure tours in the UNESCO World Heritage Site of Phong Nha-Ke Bang National Park & surrounding cave systems.

Source: The Intrepid Explorer

The Intrepid explorer