The facts
| Figure | |
|---|---|
| UNESCO | Inscribed 2003, extended 2015 and 2025 |
| Province | Quang Tri, in Bo Trach and Minh Hoa districts |
| Core zone | 857.54 km² |
| Karst age | Evolving since the Paleozoic, some 400 million years |
| Caves known | Around 300 |
| Passage surveyed | About 126 km as of 2009 |
| Phong Nha Cave | 7,729 m, 14 grottoes, a 13,969 m underground river |
| Paradise Cave | 1.1 km path, opened 3 September 2010 |
Disclosure: VietSIM sells prepaid eSIMs for Vietnam. We sell no tours and have no relationship with any cave operator here.
The timescale is the attraction
The limestone here has been evolving since the Paleozoic, roughly 400 million years ago, and no major karst area in Asia goes back further. Everything else on this page is downstream of that number.
Four hundred million years of water moving through rock is what produced around 300 known caves, about 126 kilometres of which had been surveyed as of 2009. A single expedition that year added 20 caves totalling 56 kilometres. A system that can gain that much in one season is a system nobody has finished reading.
The park was inscribed by UNESCO in 2003 under natural criteria and extended in 2015 and again in 2025. The core zone covers 857.54 square kilometres in Bo Trach and Minh Hoa districts, about 500 kilometres south of Hanoi. Note the province: it is Quang Tri, and a great deal of older writing says Quang Binh, which matters when you are searching for transport.
What you can walk into
Two caves carry ordinary visitors on foot.
Phong Nha Cave runs 7,729 metres and contains 14 grottoes and an underground river of 13,969 metres. Visitors go about 1,500 metres in, which is a fraction of it and still more cave than most people have stood inside.
Paradise Cave has a built path 1.1 kilometres long, opened on 3 September 2010. The path is the reason it works for people who are not cavers.
Son Doong is a different proposition. Its main passage runs over five kilometres, with sections 200 metres high and 150 metres wide. It is not something you add to an afternoon.
How far the cave goes, and how far you walk
Practical notes
This is the north central coast, so the wet season runs against the rest of the country’s: the month by month picture is in when to go to Vietnam. Caves flood, and access closes when they do, which is the single most important reason to check dates rather than assume.
Most people come through Hue or arrive by night bus or train on the main line, covered in sleeper buses in Vietnam and the Reunification Express. Coverage in the park is thin, so download what you need before you go in: sizing is in how much mobile data for Vietnam with the plans in the Vietnam eSIM store.