Tu Lan Cave System

The Tu Lan system lies in a separate valley from the main Phong Nha show caves, and reaching it means walking through maize fields and forest, wading rivers and then swimming into the entrances with a headtorch. Trips run from Tan Hoa village and last from one to four days, with camps set up on sandbanks outside the cave mouths. Inside are underground rivers, sculpted rock, small waterfalls and chambers the guides light with lamps. Group sizes are capped and gear is carried in by porters. It is physically involved rather than technically difficult, but the swimming sections mean departures only run when water levels are judged safe.

What you actually see

• Swimming entries - floating into cave mouths in a life jacket with a headtorch.
• Riverside camps - overnight camps pitched on sandbanks outside the cave entrances.
• Underground waterfalls - the small falls and pools inside the connected chambers.
• The valley approach - the walk through maize fields, limestone hills and forest to the system.

When to go

Trips run from roughly March to August, when water levels allow swimming; autumn floods close the valley and fill the caves. Heat and humidity peak in June and July, which makes the trek harder but the water more welcome. Departures book out over the summer holidays, so reserve well ahead. Groups leave on fixed dates rather than on demand.

Honest expectations

This is not a casual visit: expect hours of walking in wet clothes, slippery rock, and swimming in cold water in the dark, which some people find genuinely unnerving. Trips are expensive by Vietnamese standards and are not refunded if the weather turns. There is no phone signal, camp facilities are basic and toilets improvised. Anyone uncomfortable in water should choose a dry show cave instead.

Nearby

Phong Nha village and the main show caves are about an hour and a half southeast.