By the end of a trip to Vietnam, you may well be sick to death of caves – especially once you’ve been around Ha Long Bay – but if you see just one on your travels, make it Phong Nha, an otherworldly cavity only accessible by boat. It’s a whopping 8km long, but only the first kilometre or so is open to the public, but this alone is beautiful enough to make a visit worthwhile. It was revered as the largest cave in Vietnam until the discovery of the nearby Son Doong Cave, now widely regarded as the largest in the whole world.

These caves form part of the Phong Nha-Ke Bang National Park, yet to be fully opened to international visitors. It’s a place of intense beauty, at its best in the morning when banks of mist soften its jagged contours. There are other caves in the area, including the colossal Thien Duong, as well as the Nuoc Mooc eco-trail.

Brief history

Since time immemorial the underground river emerging at Phong Nha Cave has held a mystical fascination for the local population. The earliest-known devotees were ninth- and tenth-century Cham people, followed by Vietnamese who petitioned the guardian spirits during periods of drought, with great success by all accounts. When Europeans started exploring the caves early in the twentieth century it’s said the rainmaker took everlasting umbrage. However, the explorers were undeterred and by the 1950s, tunnels 2km long had been surveyed and the number of visitors warranted the construction of a small hotel. Owing to the intervening wars, when Phong Nha provided safe warehousing – you can see evidence of an American rocket attack on the cliff above the cave entrance – nothing further happened until a British expedition was allowed to investigate in 1990. They began pushing upriver, eventually penetrating deep into the limestone massif.

Phong Nha Cave

The only way to Phong Nha Cave is by boat. These seat up to fourteen people, and though it’s theoretically possible to join other groups, you’ll likely be told to charter one of your own. The boats wend their way 5km (30min) upstream to the cave entrance, after which the pilot cuts the engine and starts to paddle through. You’ll drift awhile between rippling walls of limestone, and see immense stalactites and stalagmites, all lit by multicoloured spotlights. The boat eventually draws into a small subterranean beach, from which you follow an easy, 500m-long trail around the cave (flip-flops will be fine) – note that visitors must stick to the path to avoid any risk of rock damage. Your driver will be waiting for you at the end of the path.

Tien Son Cave

You can follow up your visit to Phong Nha by taking a steep, 330-step climb up to Tien Son Cave. From here you’ll have a grand view of the valley, while inside there are Cham inscriptions dating as far back as the ninth century. Unfortunately, their magnificence is diluted somewhat by lurid lighting, presumably placed here to make for a more visually vivid experience – unless you’re a true cave fanatic, you’ll likely be happy with visiting Phong Nha alone.

Thien Duong Cave

Before the discovery of Son Doong, Thien Duong, or “Paradise Cave”, held a brief period in the limelight as the longest cavern in Vietnam. Under the same management as the Sun Spa Resort in Dong Hoi, the first kilometre or so has now been fully opened up to tourism – a truly baffling staff-to-visitors ratio shows that there are high hopes of making this one of Vietnam’s major drawcards. This partially explains the high ticket price, though this also affords you a golf-buggy ride to the trailhead, and a (largely unnecessary) guide for the cave itself. It’s a sweaty climb up, but the jaw-dropping beauty of the cavern makes such exertion worthwhile – there’s nothing in particular to see, but it’s simply a joy to be walking in a cavern of such unworldly size – in places, over 100m in both height and width.

Nuoc Mooc Eco-trail

Sprawling along picturesque riverside territory and lassoed together with bamboo bridges, this 1km-long eco-trail shows the reassuring direction in which local tourism is heading. You’re highly unlikely to see any animals, but there are a couple of opportunities to swim – the entry price will see your bags taken care of, though you’ll have to pay extra for drinks.

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