Hang En in Vietnam is one of the largest caves in the world, yet as we clambered over the jagged rocks at its entrance, the sheer magnitude of the space remained hidden. The cave finally expanded to reveal its true scale, and my sense of self shrank. Inside, a calm lake lapped at the sand that was dotted with tents—our accommodations for the night. Sunlight poured through the cave’s gaping mouth, turning the water a glistening turquoise and the sand a Caribbean white. As we forged on toward the beach, a renewed sense of excitement urged us on after the sweltering trek through the jungle.
At almost 476 feet high at its tallest point and with a volume of 6.7 million cubic meters (more than 2,500 Olympic-sized swimming pools), Hang En is vast. It’s located deep within Phong Nha-Ke Bang National Park in the Quang Binh Province of north-central Vietnam. UNESCO added the park to its World Heritage List in 2003, calling it home to “one of the most outstanding limestone karst ecosystems in the world.” Karst landscapes are characterized by soluble rocks, such as limestone, that erode to form caves and sinkholes, as well as cliffs and pillar-like rock formations above ground. The national park comprises limestone plateaux, tropical forests, and more than 64 miles of caves and underground rivers.
Meaning “swift cave” in Vietnamese, Hang En has been known to local inhabitants for hundreds of years. The nomadic Arem people, who named the cave after the birds that built their nests within its ceiling, used it for shelter.
In 1990, a local man named Hồ Khanh learned about the cave while searching for fragrant agarwood deep in the forest. Then in 1994, a team of Vietnamese experts and members of the British Cave Research Association (BCRA) surveyed it, inviting the rest of the world to learn about this subterranean wonder. Over the years, Hồ Khanh built a relationship with the scientists and, in 2009, when they returned to the area to carry out more surveys, he led them to the entrance of nearby cave Son Doong, which he had initially stumbled upon in 1991. Son Doong, fed by the same river as Hang En, turned out to be the world’s largest known natural cave by volume, at 38.5 million cubic meters.
Since Phong Nha-Ke Bang National Park is protected by the Vietnamese government, there are a few hoops to jump through that make getting to Hang En a journey on its own. You can only access the cave on a group tour with operator Oxalis, and you can only get to it by trekking approximately seven miles through the jungle (it’ll be another seven-mile hike out).
The two-day, one-night Hang En Adventure starts around 7:30am with a hotel pick-up in the village of Phong Nha. (Alternatively, you can get yourself to the Oxalis office in Phong Nha at the designated time.) After a detailed safety briefing, you’ll be given your helmet and headlamp (and hiking shoes if you don't have your own) and set off to the trek’s starting point, a 15-minute drive away.
The trek winds through thick tropical forest and open karst landscapes dotted with soaring limestone rocks; it also involves wading through numerous streams and creeks. After about one and a half hours, the tour stops for lunch in the tiny jungle village of Doong—home to the Bru Van Kieu Indigenous people who live throughout Thailand, Laos, and Vietnam. You’ll then continue for another three hours to Hang En, where you’ll strap on your helmet and headlamp and prepare to venture into the cave.
A group of staff and porters travels ahead of the group, so by the time you arrive, your tent is set up and dinner is being prepared. The multicourse meal, which can be made vegetarian or vegan upon request, features Vietnamese specialties, such as stir-fried vegetables with soy sauce, spicy tofu, and rice cooked to perfection, and is served at an atmospheric dining area. Post-trek, it feels blissful to sit on blankets around the low, candlelit table and enjoy your well-earned meal while chatting with fellow adventurers about an unforgettable day.
You take a tiny cable ferry across the lake to the beach, where you can relax, enjoy the cool interior climate, and take a swim in the natural pool. According to Oxalis, the water in the cave hovers around 63–77°F, warm in the winter and cooler in the summer. Look out for resident wildlife, such as squirrels, monkeys, and, at dusk, huge bats known as flying foxes—all of which can be spotted at the entrance of the cave, a safe distance from the camp. If you’re interested in insects, there are all kinds of weird and wonderful creatures, like centipedes and pseudoscorpions, inhabiting the darker areas of the cave floor.
Then it’s time to climb into your tent for a night in what must be the world’s most unique campsite. Due to the acoustics of the cave, small sounds are greatly amplified. As we curled up in our sleeping bags we could hear the whispers of our fellow campers and the nighttime cacophony of the jungle outside. Despite that, we slept soundly, woken early by morning sunlight streaming into the cave.
Getting there
- Getting there: Most international flights to Vietnam arrive in Ho Chi Minh City at Tan Son Nhat International Airport (SGN) or Da Nang at Da Nang International Airport (DAD). From one of these, you can take a regional flight to Dong Hoi’s domestic airport (VDH), located about 28 miles (about a 50-minute drive) from Phong Nha, where the tour sets off from. You can also take a 6.5-hour train ride from Da Nang to Dong Hoi and continue by taxi or bus to Phong Nha.
- Average Going price for cheap flights to Vietnam: $692 roundtrip
How to do it
- Best time to go: Due to weather restrictions, the Hang En tour operates from December to mid-September. Between January and March, it can be cold, but there are some warm, sunny days. (When I was there in January, it was nice and warm, if a little muddy in the jungle.) During spring (April–May), expect mild, sunny weather and lots of blooming flowers. Summer runs from June to August, so it will be very hot, but the jungle and cave provide decent protection from the sun.
- Cost: The two-night, one-day Hang En Adventure costs just over $300 per person depending on the exchange rate.
- Tips: Oxalis rates the Hang En overnight tour moderate in terms of difficulty, asking that participants have recent trekking experience. The company will provide a detailed checklist of equipment that you’ll need to bring with you, including a backpack, appropriate clothing (which protects you from leeches, which are common in this ecosystem), and boots with good drainage; Oxalis provides suitable footwear if needed, but it’s best to bring your own broken-in boots to ensure a good fit and avoid blisters. Learn more about preparation and the equipment that you’ll need here.
