My unforgettable experience camping inside the world’s biggest cave

It’s dark inside the cave and I wake up in my tent sweat-drenched, despite having kicked off my sleeping bag and pyjamas in my sleep. Hungry for fresh air, I slip on some clothes before fumbling around for my flip-flops. After sliding out from my cocoon, I absorb my surroundings through bleary eyes. Within a second I’m wide awake, my mouth agape. Looming above is a 280-metre-wide ceiling collapse, a celestial portal to a starry midnight sky.

I’m camped within central Vietnam’s Hang Son Doong — the world’s biggest cave by some measures — which lies buried in Phong Nha-Ke Bang National Park. Hang Son Doong makes headlines for its superlative size, but it’s the two ceiling collapses that lend its otherworldly atmosphere. According to British caver Howard Limbert, who led the inaugural survey here in 2009, the collapses were caused by a seismic event around half a million years ago. They are large enough to invite cascades of light that nourish thriving underground jungles.

Hang Son Doong has only been open to the public since 2013, but its unique natural splendour and size tempted developers to propose a cable car the following year. The proposal was met with fierce opposition from local pressure groups, tourism experts and cavers, who warned that a cable car — and its attendant hordes of tourists — would cause irreparable damage.

UNESCO also voiced concern, having designated Phong Nha-Ke Bang National Park a World Heritage site in 2003. Back then, only one man knew Hang Son Doong even existed.

Local jungle explorer Ho Khanh serendipitously discovered Hang Son Doong in 1990 while seeking shelter from a storm. His subsequent attempts to find the cave again were fruitless until 2008; a year later, Ho guided Limbert and his team to the opening. The cavers surveyed Hang Son Doong and determined it contained the biggest known underground chamber on Earth.

The national park granted local tour company Oxalis Adventure exclusive rights to conduct tours — like the one I’m on — in 2013. The tours span three nights, two of them spent within the nine-kilometre-long Hang Son Doong and one in Hang En, a neighbouring cave. An Oxalis Adventure tour remains the only way to explore the cave, and each one is restricted to 10 customers, ensuring fewer than 1,000 tourists visit each year. By contrast, a cable car would ferry thousands of tourists each day.

The cable car plans were shelved in 2019, but the argument sparked discussion over how Phong Nha, as the destination is known, can develop sustainably. That debate endures today; in March, a Euromonitor International report ranked Vietnam 96 out of 99 countries for sustainable tourism.

However, Nguyen Chau A, founder and CEO of Oxalis Adventure, believes tourism can protect the environment and generate jobs in one of Vietnam’s poorest provinces — and the two are linked. Since the rediscovery of Hang Son Doong, almost 30 different caves in the area have opened to the public.

His company employs more than 500 people in the destination as tour guides, porters and office workers. Besides the fact that providing locals with a regular income improves their standard of living, “this means they no longer have to support their families through illegal logging and hunting,” he says.

Phong Nha-Ke Bang National Park achieved its status as a UNESCO World Heritage site partly because of its rich biodiversity. The protected area is home to thousands of plant species and hundreds of animal species. But this biodiversity has suffered in recent decades, as poverty drove many locals into the jungle in search of sellable resources, such as rare agarwood trees and endangered pangolins.

“People did what they had to do to survive,” says Ho Trong Dai, a tour guide at Oxalis Adventure and Ho Khanh’s nephew. Ho received a university education and studied for his tour guide license, but he laments that those around him weren’t all so fortunate. “I never had to make a living in the jungle, but my friends did.” Now, however, people in Phong Nha no longer make money by taking from the forest: Around half of them do farming and the other half work in tourism, Ho explains.

Hang Son Doong’s rediscovery and the subsequent influx of visitors led to the launch of activities beyond caving, including kayaking, trekking, ziplining, cycling and motorbiking. Phong Nha could become a model for sustainable tourism in Vietnam, but only if “there is a diversity of things to do,” says Nguyen Thanh Hai, a conservationist who opened Hai’s Eco Tours in 2016.

Nguyen’s company takes tourists on trekking and camping trips through the national park, as well as guided tours to the wildlife rescue centre where he used to work. “I wanted to find a way to support the centre, which is desperately underfunded,” says Nguyen. Over the years, the centre has housed bears, civets, langurs and macaques, to name just a few animals.

According to Nguyen, if Phong Nha can offer more diverse activities, it will appeal to more people. Visitors will also be more likely to stay longer, potentially transforming Phong Nha into a year-round destination. This is especially important considering many caves are flooded and inaccessible for up to a third of the year. Tours to Hang Son Doong, for example, only happen January to August.

In some ways, Phong Nha is a sustainable tourism success story, but the increase of visitors has also led to tension. Australian national Ben Mitchell moved here in 2007 and opened a simple homestay with his wife in 2009. Now he has a network of boutique accommodations in the area, including Phong Nha Farmstay and Victory Road Villas. Mitchell remembers the sharp increase of visitors after the Hang Son Doong rediscovery, which led to an even sharper increase in budget lodgings.

“By 2016, everyone was undercutting each other,” says Mitchell. “It was a great race to the bottom — and nobody was benefiting.” While the number of visits to most caves is strictly regulated by the authorities, almost anyone in Phong Nha can open a basic dorm or homestay, regardless of quality. Nevertheless, Mitchell is optimistic about Phong Nha’s accommodations in the future. “If there can be some form of organization like a local tourism association, things will improve,” he says.

I first visited Phong Nha in 2008 when international travellers here were few and far between. Since then, I’ve seen the developing tourism generate local employment and contribute to conservation efforts. The crowds have been averted — at least for now. Currently Vietnam’s borders are sealed due to the pandemic, and although domestic tourism has kept Phong Nha afloat, the absence of inbound visitors is still keenly felt.

But like Mitchell, I remain quietly optimistic about the destination’s future as an exemplar of sustainable travel. With so many of Vietnam’s highlight destinations — such as Halong Bay and Hoi An — buckling under the pressure of over-tourism in the years leading up to the pandemic, it has never been more important for Phong Nha to show there’s a better way.

Tour was provided to Hanoi-based freelance writer Joshua Zukas by Oxalis Adventure. They did not review or approve this article.

The Star understands the restrictions on travel during the coronavirus pandemic. But like you, we dream of travelling again, and we’re publishing this story with future trips in mind.