The caves of Phong Nha, from a boat ride to a sold-out expedition

The Phong Nha caves include the largest cave passage on earth and several you can walk into for the price of a decent lunch. The gap between those two facts is the whole planning problem: the caves here range from a 205,000-dong boat ride to a multi-day expedition that is sold out two years ahead.

What does it cost to visit the caves at Phong Nha?

Less than most people expect, for the accessible ones. Phong Nha Cave is 150,000 dong to enter, plus about 55,000 dong for a place in the river boat — around 205,000 dong a head. Paradise Cave is 250,000 dong, with an optional electric buggy from the car park at 15,000 dong one way.

Bring cash. Ticket counters at the park generally do not take cards, and the nearest reliable ATMs are back in the village. Vietnam's ATM fee structure makes one larger withdrawal the sensible move anyway.

Which cave should you actually visit?

Phong Nha Cave and Paradise Cave, in one day, if you only have one. They are the two accessible headline caves and they are not the same experience twice.

Phong Nha Cave is entered from the water. A boat runs up the Son river, cuts its engine at the mouth, and is rowed into the passage. That approach is the thing people remember, and the photograph at the top of this page is exactly it — the blue boats waiting at the entrance.

Paradise Cave is the opposite: a climb from the road, then a wooden boardwalk into an enormous dry chamber full of formations. It is bigger, drier and better lit, and it involves more walking before you see anything.

Can you visit Son Doong, the biggest cave in the world?

Only through Oxalis Adventure, and only if you plan years out. Oxalis is the single operator licensed by the national park to run Son Doong, the expedition runs several days with a full support team, and it costs on the order of 3,000 US dollars per person.

Availability is the real barrier rather than the price. The 2026 and 2027 departures are sold out, and 2028 is what is currently open for booking. Anyone deciding this year is deciding about a trip two years away.

What is the alternative if Son Doong is full?

Hang En, which is the same idea at a fifth of the cost. The overnight trip walks in through jungle and river crossings and camps on a sand beach inside the cave, under an entrance big enough to hold weather of its own.

Hang En runs around 8,800,000 dong, roughly 333 US dollars in mid-2026, and that figure covers guides, park fees, camping and caving equipment, and meals. It books months rather than years ahead. For most people it is the version of this experience that actually happens.

Do you need a guide, or can you do this yourself?

For the ticketed caves, yourself. Phong Nha Cave and Paradise Cave are both bought at a counter and entered on a boat or a boardwalk, with no operator in between. A rented motorbike or a hired driver from the village reaches both, and the two together are a comfortable day.

Everything past the boardwalk is operator-only, and that is a licensing rule rather than a sales pitch. The national park permits specific companies to run specific caves, which is why Son Doong has exactly one operator and why the adventure caves cannot be walked into independently.

The practical split is simple. If a cave has a ticket counter, go alone. If it involves a night, a river crossing or a rope, it is booked in advance with the company licensed to run it.

When are the caves open?

February to August, and February to April for the best of it. That is the dry stretch on this part of the coast, when the caves are fully open and the walking approaches are not wading.

The autumn is the one to avoid. Central Vietnam takes its heaviest rain from September, and high water on the Son river can close the boat caves with no notice. This is the same seasonal pattern that governs Hue and the rest of the centre.

How long does Phong Nha need, and how do you get there?

The village itself, where to sleep and what else is there is covered in the Phong Nha guide.

Two nights, three if you want a cave overnight. One full day covers the two ticketed Phong Nha caves comfortably; a second buys Hang En, the Dark Cave, or the countryside around the village.

The town is inland from Dong Hoi, which sits on the main north-south railway and has its own airport. Coming from Hue or Hanoi, the train to Dong Hoi followed by a road transfer is the usual route, and the transport guide has the fares and journey times.