Designated a Unesco World Heritage site in 2003, the remarkable Phong Nha-Ke Bang National Park contains the oldest karst mountains in Asia, formed approximately 400 million years ago. Riddled with hundreds of cave systems – many of extraordinary scale and length – and spectacular underground rivers, Phong Nha is a speleologists’ heaven on earth.
The Phong Nha region is changing fast. Son Trach town (population 3000) is the main centre, with an ATM, a growing range of accommodation and eating options, and improving transport links with other parts of central Vietnam.
The caves are the region’s absolute highlights, but the above-ground attractions of forest trekking, the area’s war history, and rural mountain-biking means it deserves a stay of around three days.
Hang Son Doong
Hang Son Doong (Mountain River Cave) is known as the world’s largest cave, and is one of the most spectacular sights in Southeast Asia. The government approved (very restricted) access to the cave system in June 2013. The only specialist operator permitted (by the Vietnamese president no less) to lead tours here is Son Trach–based Oxalis.
Son Doong is no day-trip destination; it’s in an extremely remote area and the only way to visit is by booking a four-night/three-day expedition with around 16 porters. It costs US$3000 per person, with a maximum of 10 trekkers on each trip.
This enormous cave was discovered quite recently. Ho Khanh, a hunter from a jungle settlement close to the Vietnam–Laos border, would often take shelter in the caves that honeycomb his mountain homeland. He stumbled across gargantuan Hang Son Doong in the early 1990s, but the sheer scale and majesty of the principal cavern (more than 5km long, 200m high and, in some places, 150m wide) was only confirmed as the world’s biggest cave when British explorers returned with him in 2009.
The expedition team’s biggest obstacle was to find a way over a vast overhanging barrier of muddy calcite they dubbed the ‘Great Wall of Vietnam’, which divided the cave. Once they did, its true scale was revealed – a cave big enough to accommodate a battleship. Sections of it are pierced by skylights that reveal formations of ethereal stalagmites that cavers have called the Cactus Garden. Some stalagmites are up to 80m high. Cavers have also discovered colossal cave pearls measuring 10cm in diameter, which have been formed by millennia of drips, fusing calcite crystals with grains of sand. Magnificent rimstone pools are present throughout the cave.
Tu Lan Cave
The Tu Lan cave trip begins with a countryside hike, then a swim (with headlamps and life jackets) through two spectacular river caves, before emerging in an idyllic valley. Then there’s more hiking through dense forest to a ‘beach’ where rivers merge; this is an ideal campsite. There’s more wonderful swimming here in vast caverns. Moderate fitness levels are necessary. Tu Lan is 65km north of Son Trach and can only be visited on a guided tour.
Longer Tu Lan tours are also available. The longer excursions penetrate deeper into the jungle, but as the region is so pristine even day hikes are rewarding. Howard and Deb Limbert, consultants to tour operator Oxalis, discovered these caves in 2010. See the Oxalis website for details and costs of longer tours.
This gigantic cave is very close to Hang Son Doong, and featured in the same National Geographic photographic spread in 2011. Getting here involves a trek through dense jungle, valleys and the Ban Doong minority village, a very remote tribal settlement (with no electricity or roads). You stay overnight in the cave or in a minority village. Tours can be booked via Oxalis or local accommodation.
Incorporating an above-water zip line, followed by a swim into the cave and then exploration of a pitch-black passageway of oozing mud, it’s little wonder Hang Toi is the cave experience you’ve probably already heard about from other travellers. Upon exiting the cave, a leisurely kayak paddle heads to a jetty where there’s more into-the-water zip-line thrills to be had.
Phong Nha Cave & Boat Trip
The spectacular boat trip through Phong Nha Cave is an enjoyable, though touristy, experience beginning in Son Trach town. Boats cruise along past buffalo, limestone peaks and church steeples to the cave’s gaping mouth. The engine is then cut and the boats are negotiated silently through cavern after garishly illuminated cavern. On the return leg there’s the option to climb (via 330 steps) up to the mountainside Tien Son Cave (80,000d) with the remains of 9th-century Cham altars.
Surrounded by forested karst peaks, this remarkable cave system extends for 31km, though most people only visit the first kilometre. The scale is breathtaking, as wooden staircases descend into a cathedral-like space with colossal stalagmites and glimmering stalactites. Get here early to beat the crowds, as during peak times (early afternoon), tour guides shepherd groups using megaphones. Paradise Cave is about 14km southwest of Son Trach. Electric buggies (per person one-way/return 15,000/25,000d) ferry visitors from the car park to the entrance.
To explore deep inside the cave, consider booking a 7km Paradise Cave tour (2,650,000d, minimum two people), which includes a swim through an underground river and lunch under a light shaft. Bookings can me made through Phong Nha Farmstay and Easy Tiger.
The largest part of the Tu Lan cave system, this moderately challenging cave was opened to visitors in 2016. The 10- to 12-hour day adventure includes a jungle walk, and the cave is studded with verdant ferns and rimstone pools.
Discovered in 2012, and opened to visitors in 2015, Hang Va is explored on a two-day/one-night excursion that first travels along an underground river in Hang Nuoc Nut. Tours overnight in a jungle camp at the entrance to Hang Va, where the cave’s highlight is a spectacular stalagmite field partly submerged in crystalline waters. Ropes and harnesses are used extensively.