By: Chris Humphrey


Since 2014, one of the world’s largest cave systems, the Son Doong cave near the Laotion border in Vietnam’s Quang Binh Province has been under threat from developers planning to construct a cable car that would carry thousands of tourists daily.

Some are pointing out that this could also irreparably damage the area’s primary forests. A movement to stop the cable car reaching the area, spearheaded by Vietnamese environmentalist Huong Le, has gained traction over the last three and a half years. Huong has been involved in efforts to garner what total more than 170,000 signatures against the proposed development.

The caves in question, which feature some of the world’s largest stalactites and cave pearls, are truly remarkable. Located in a UNESCO’s World Heritage site called Phong Nha-Ke Bang National Park, Son Doong cave is so large it contains a fast-flowing, subterranean river, two jungles, a beach that visitors can camp on overnight, and seven endemic species that don’t exist anywhere else in the world. It has the largest cross section of any cave – twice that of its nearest rival – and is tall enough to fit in a 40-story building.

Tetracoral fossils within the cave. (Photo courtesy Professor Phuong Ta)

Currently, a sustainable eco-tour brings fewer than 800 people to Son Doong annually. In comparison, the proposed cable car would bring about 1,000 people every hour, a shift that would threaten the pristine ecosystems within the cave.

Many also fear the construction needed for the cable cars would damage forest near the entrance and put pressure on the cave’s fragile roof, potentially triggering further dolines, which is when the roof of the caves collapses due to limestone erosion.

Cave Pearls within the rimstone system. (Photo courtesy Professor Phuong Ta)

The Vietnamese real estate company Sun Group initially proposed construction of a cable car in 2014, but scrapped the plans entirely, Huong believes, due to public support for the petition. In the summer of 2017, Vietnamese Prime Minister Nguyen Xuan Phuc approved a new plan to build a cable car into nearby En Cave (the world’s third largest), this time headed by Vietnamese real estate giants FLC Group. Since then, the company has kept quiet about their plans for the project.

Efforts to stop the cable car, however, have been gathering pace. And in a nation where historically the Communist Party of Vietnam has not supported organized expression of collective identity, social media has, to an extent, provided a platform for civil society movements to form.

Huong Le’s Save Son Doong Facebook page, for example, has gained hundreds of thousands of followers. It propelled her to a speaker’s spot at a TEDx event that I attended in Hanoi this June. Her brave, spirited speech, which covered not only the caves, but also the issue of political transparency in Vietnam, drew tears from the audience, wild applause, and a standing ovation.

Large rimstone system near the second doline. (Photo courtesy Professor Phuong Ta)

Huong works full-time at Saigon’s Fulbright University as an admissions officer and dedicates her free time to the Save Son Doong campaign. Her efforts earned her a place on Forbes Vietnam’s 30 under 30 list earlier this year, a scholarship to study in the US and even a chance to speak to Barack Obama during his state visit to Vietnam in 2016. Obama later declared in his address to the nation that Son Doong Cave should be preserved for future generations.

The core message of Huong’s TEDx speech was the importance of protecting the fragile ecosystems within the cave. Between 2 and 4 million years old, the caves have been untouched by human hands for millennia and, as a result, pristine ecosystems have thrived within.

With two dolines already puncturing the roof, light has been able to enter, creating some of the largest areas of intact primary forest anywhere in Vietnam and an impressively high level of biodiversity: over 800 vertebrate species have been recorded in the area, including 154 mammals, 117 reptiles, 58 amphibians, 314 birds, and 170 fish.

Sand Towers inside Son Doong Cave. (Photo courtesy Professor Phuong Ta)

Phuong Tạ, head of Hanoi University’s ecology department and the first scientist allowed to explore and study the caves, has been instrumental in inspiring and informing Huong.

“Each cave is a separate world, an individual ecosystem,” Phuong said. “Each one has a different temperature, humidity and air quality. All of this creates an ecosystem in which only a few animals can adapt and survive.”