Following Bamboo’s lead, we dropped our bags into the water and rolled onto our backs to swim slowly, slowly deeper into the cave. Bats swooped and dived, feeding on the thousands of tiny flies illuminated by the torch light. After a few hundred metres the sound of rushing water grew more intense as we reached the cave’s exit. The sense of discovery on emerging was even more palpable than that inside. Already in a remote part of Vietnam, we now found ourselves in what seemed like another world, emerging on a beach fronted by an impossibly pretty turquoise lake, which was fed by a waterfall thundering from the cave mouth.
The next cave we were to tackle was discovered by chance by a Dutch tourist named Kim. Also on the Tu Lan Trek, he’d sauntered off to find a quiet spot to relieve himself, away from the lagoon, and found what was subsequently christened Kim Cave. We swam through the chamber’s river to reach our campsite for the night: tents and hammocks had already been set up on the edge of an emerald-green lagoon. With time for one more adventure before supper, we swam across the water to Tu Lan Cave, after which the whole two-day adventure is named.
Inside, we ducked and weaved amid a labyrinth of stalactites, stalagmites and columns, sometimes having to pass backpacks through first in order to squeeze by. The cavern then opened up to reveal a bizarre set of shelves formed over thousands of years and containing almost perfectly round balls of calcium – cave pearls. Surrounding this, the walls were laced with a golden, glistening mineral and yet more shining eyes of innumerable huntsman spiders.
What else lies beneath? – Back at the campsite, we freshened up in the waterfall’s plunge pool as the sun sank swiftly behind the hills. Ravenous, we feasted on tender pork barbecued on spits over open flames accompanied by a local speciality dipping sauce of lime leaves, lime juice, garlic and chilli. With a glass or two of lethally strong rice wine, we kicked back to watch the stars. As we lazed, Bamboo pointed out two pairs of twinkling dots in the bushes – the eyes of flying foxes, quietly observing us from a distance. After a well-earned sleep – some of us in tents, others opting for swaying hammocks – we made our way into the massive arch of Ken Cave and lowered ourselves into its dark river waters.
Reaching the final stop of the two-day journey also involved its hardest swim, paddling 150m against the current. We re-grouped at the foot of a steep climb and ventured upward in single file before reaching a sheer drop-off. In front of us was a colossal column formed by the meeting of a stalactite and stalagmite. By now we’d seen tens of columns, but this one was in a league of its own. Photographs of what stood before us went viral a couple of years ago, so we had all seen it before, but we were still taken aback by its sheer scale and the surreal morphing of orange and cream hues on its richly textured surfaced.
The final cave tackled, we shed our lifejackets, helmets and headlamps and prepared for the trek back to base. For some, this proved the most challenging aspect of the trip, with the path climbing steeply through dense, primary forest in hot, steamy conditions. In places the thin, slippery trail snaked around vertiginous deep drop-offs – this was not a place where you wanted to put a foot wrong. After a couple of hours we found ourselves back at the river that we’d waded across the morning before, and over-heated members of the group collapsed gratefully into its cooling flow. Later, exhausted but content back at the Tu Lan base, we swiftly emptied its fridge of cold beers.
An uncertain future – That evening I went out for dinner with Chau A Nguyen, founder of Oxalis Adventure Tours, which runs the Tu Lan Trek. The day before, Chau and his team had been in the nearby city of Dong Hoi, anxiously waiting to hear whether the local authorities would allow tours of Son Doong to continue. When we met, the good news was writ large on his face. Chau spoke of his pride at helping develop the area from a tourist backwater – but he also voiced his fears for the future. There are now plans for a cable car project in the area, which would take people right to the mouth of Hang Son Doong. This would transform the town of Phong Nha as well as the UNESCO-listed cave area.
Tourist numbers would sky-rocket, and there are fears that the construction itself would have a devastating impact on the environment. On the flip-side, investors argue that cable cars have been built at sites of outstanding natural beauty before and that the project would inject much-needed capital into this relatively poor province. For now though, this is a region that remains pristine and ripe with the promise of adventure. And with Howard and Chau talking about the potential discovery of even more lengthy caves hidden deep in within these hills, who knows what adventures are still waiting to be revealed.
