Inside Vietnam’s most amazing caves

The little engine cuts out and our blue dragon boat drifts towards the dark maw at the base of the limestone cliff. Its monotonous putt-putt is replaced by the gentle lapping of the Son River and the occasional clunk of the oars being operated by our two-person crew. As Phong Nha Cave’s ceiling glides over us, the crew pause from their efforts to slide back the boat’s roof, allowing us unfettered views of the wonders enveloping us.

A droplet of water splashes on my neck and tiny bats flutter erratically overhead, but my attention is focused on the huge globular stalagmites rising from the river’s edge. As we float deeper underground, each twist and turn in the narrow cavern reveals another striking vista crowded with stalactites and stalagmites. At the 1.5-kilometre mark, the crew turns the boat around and we head back towards the entrance, but not before marvelling at an eerily lit column in an adjoining cavern. Just before we emerge into daylight, the boat pulls over to a small landing area and we disembark for a short walk through Court Cave, so named because the formations resemble those in a royal court.

Vietnam’s impressive collection of caves has only come to travellers’ attention fairly recently, but it’s beginning to generate a significant buzz. Much of the country’s north is built on a layer of 200 to 400-million-year-old limestone that has been pushed, pulled and folded by tectonic forces into mountains and hills, which have eroded away to form the iconic marine pillars of Ha Long Bay. Rainwater has slowly dissolved the limestone to create a complex maze of deep caverns that includes several of the world’s largest.

Underground adventure

The epicentre for Vietnamese caving is in World Heritage-listed Phong Nha-Ke Bang National Park, about 60 kilometres north-west of the beach-side city of Dong Hoi, itself an overnight train ride from Hanoi or a flight from Ho Chi Minh City. The 343,000-hectare park boasts sheer limestone cliffs, sparkling waterfalls, rugged river gorges, thick jungle, endangered wildlife and a bewildering array of caves and grottoes – at least 300 recorded so far with a total length of more than 125 kilometres.

With so much on offer, it’s no surprise that visitors have a range of options, from sedate self-guided tours to adventurous multi-night expeditions. For the former, top of the list is Paradise Cave, discovered by a local in 2005 and opened to the public in 2010. The cave’s modest entrance belies the wonders within. A sturdy wooden staircase descends into an enormous cathedral-like space decorated with glittering stalactites and stalagmites before joining a kilometre-long fenced boardwalk that snakes through the cavern.

Solid curtains of limestone hang from the ceiling; multi-tiered wedding cakes sprout from the floor, their sides dripping with limestone icing; and glistening waves of limestone cascade down like frozen waterfalls. In keeping with the cathedral theme, there’s a wall of limestone columns that resembles an enormous pipe organ. As impressive as these formations are, it’s the cavern itself that takes the breath away – in places, it’s more than 70 metres high and 150 metres wide.

Among the most popular of the park’s other caves is Hang Toi, or Dark Cave. As the name suggests, this six-kilometre cavern is unlit and the day-long guided tour has been designed to eke out as much adventure as possible: Vietnam’s longest zipwire provides an exciting way to get there and the tour includes a swim in a subterranean river, a wallow in a mud pool, kayaking and an over-water obstacle course. There are also several options for overnight treks, including Hang En, the world’s third-largest cave, and the more technical Hang Va, which boasts a spectacular partly submerged stalagmite field.

Get in quick

All of these experiences lead to the pinnacle: Hang Son Doong, the world’s largest cave. It is big enough to fly a Boeing 747 through or accommodate a New York City block, complete with 40-storey buildings. However, it’s tricky to visit, the only available tour costs USD $3000 and the 500 spots available each year sell out well in advance.

Phong Nha-Ke Bang’s caves still qualify as hidden gems, but for how much longer? Tourism in the region is rapidly ramping up; there’s even talk of building a cable car to ferry visitors to the mouth of Hang Son Doong. Now’s the time to explore these subterranean sights.

Five more caves to explore

1. Nguom Ngao: Created by an underground river, Nguom Ngao in Cao Bang province is one of Vietnam’s most spectacular cave systems.
2. Ha Long Bay: Ha Long Bay’s archipelago of almost 2000 islands contains many caves, the more famous of which include Hang Trinh Nu, Hang Sung Sot and Hang Thien Cung.
3. Hospital Cave: Located on Cat Ba Island, this remarkable cave contains a three-storey complex that served as a secret hospital and safe house for leaders of the North Vietnamese army during the Vietnam War.
4. Am Phu: This huge cave in the Marble Mountains on the outskirts of Da Nang contains a lurid depiction of a Buddhist hell created by local artists.
5. Hang Pac Bo: History buffs may want to check out Hang Pac Bo, the cave in which Communist revolutionary leader Ho Chi Minh spent a few weeks in 1941 after re-entering Vietnam from China.