Kong Collapse

Kong Collapse is the deepest sinkhole in Vietnam, around 450 metres from rim to floor, and descending into it is the hardest trip sold in Phong Nha: a five-day, four-night expedition with Jungle Boss at 35,000,000 VND, minimum age 16, with a medical check required before your booking is confirmed. This page is for two kinds of reader, the one deciding whether to commit to the descent, and the one who wants to see the sinkhole without it, which is possible for roughly a third of the price on a different trip.

The centrepiece is the rope work. The route down covers roughly 100 metres of descent in staged sections, each stage rigged with a backup line and controlled by safety staff. It is a controlled abseil rather than a single free drop, but it is genuinely vertical, and there is no version of it that does not involve trusting a rope over real height. That is exactly why the operator requires a health statement and a medical check, caps groups at 10, and runs departures only on Tuesdays and Fridays. No prior climbing experience is required, and the team trains you on the techniques, but this is the trip in the park where fitness and nerve both get spent.

Around the descent sits a full expedition: five days of jungle trekking and cave travel through Phong Nha-Ke Bang National Park, with camps along the way and porters and safety staff throughout. The sinkhole itself is the payoff, a collapse so large that jungle grows down inside it, with the rim high above you by the time you stand on the floor. Few people on earth have been down it, which is part of the appeal and part of the price.

If the descent is not the appeal, you do not need the five-day trip. The three-day Tiger Cave Series Adventure, at 12,500,000 VND, camps at the edge of the sinkhole on its second night, so you look into Kong Collapse and sleep beside it without going over the rim. For most travellers who simply want to see the thing, that is the better-value choice, and it also passes through Tiger Cave, Hang Over and Hang Pygmy on the way. Both trips run with Jungle Boss, and the discount code JBR5 takes 5% off at checkout.

Timing matters more here than on gentler trips. The dry season runs February to August, with March and April the sweet spot; from September to November, flooding closes the expedition caves and this trip does not run. The cave sections hold around 23C year round, but the jungle days from May to September are seriously hot, which on a five-day expedition is worth planning around rather than discovering.

The expedition runs from the Phong Nha area, and the approach is the standard one for the region. Dong Hoi is the gateway, about 45 km away, with an airport and a mainline station: about 3 hours by train from Hue, 4 to 5 from Da Nang and about 10 from Hanoi, where the overnight sleeper works well before a trip this physical. From Dong Hoi it is 45 to 90 minutes by taxi to Phong Nha, or about 90 minutes on the local bus for around 35,000 VND. Given the fixed Tuesday and Friday departures, build your travel days around the tour rather than the other way round, and arrive a day early so a late train cannot cost you the expedition.

Don't miss

• Vietnam's deepest sinkhole, around 450 metres from rim to floor
• Roughly 100 metres of staged rope descent, each stage rigged with a backup line
• Found by drone in 2019; first tours ran in 2021
• Five days and four nights with Jungle Boss at 35,000,000 VND
• Minimum age 16, groups capped at 10, departures Tuesday and Friday
• Medical check required before booking is confirmed
• The three-day Tiger Cave series camps at the rim for 12,500,000 VND without the descent

Good for

Getting there

Know before you go

• A health statement and a medical check are required before your booking is confirmed, so start that process early.
• Minimum age 16, groups capped at 10, and departures run only on Tuesdays and Fridays. Plan your travel around the tour.
• The descent is a controlled abseil in stages with a backup line on each, not a single free drop, but it is genuinely vertical and there is no way to opt out halfway.
• You can see the sinkhole without descending it: the three-day Tiger Cave series camps at its edge for 12,500,000 VND.
• The trip does not run from September to November, when flooding closes the expedition caves.
• Cave sections hold around 23C, but jungle days from May to September are seriously hot. Train for heat as well as distance.
• Arrive in Phong Nha at least a day before departure so a delayed train or flight cannot cost you the expedition.

A bit of history

Kong Collapse was found by drone in 2019, which says something about how unmapped this part of Phong Nha-Ke Bang still is: a sinkhole around 450 metres deep, sitting under the flight path of a survey drone, unknown to the outside world until one flew over it. The name comes from the resemblance of the collapse to King Kong's head. What followed the discovery was slower than the headlines: more than two years of survey work with American caving specialists before an operating licence was granted, with the first commercial descents running in 2021. That timeline, drone find to licensed expedition in about two years, is fast by the standards of the park, where some caves wait decades between discovery and opening, and it made Kong Collapse the flagship hard trip of the operator that surveyed it.