Tour operator, Phong Nha, Quang Binh, now part of Quang Tri province
Oxalis Adventure
Oxalis Adventure is the Phong Nha operator behind the Son Doong Cave Expedition, and the only company licensed to take visitors into the largest cave on earth. Founded in 2011 and built alongside the British-Vietnamese caving expeditions that surveyed the region, Oxalis also holds the licences for Hang En, among the largest caves anywhere, and the entire Tu Lan system near Tan Hoa including Hang Tien. Their trips run on a permit system agreed with the national park, which is why the flagship expedition is capped at roughly a thousand places a year and books out far in advance.
Founded
2011, in Phong Nha
Based
Phong Nha, Quang Tri (formerly Quang Binh)
Known for
Son Doong, the largest cave on earth, sole licensed operator
Also runs
Hang En, Hang Va and the Tu Lan system including Hang Tien
Prices
8,800,000 to 79,500,000 VND per person
What is actually on the record
Every item here is checkable. We have left out the things that are not.
The Son Doong licence
Son Doong has been open to visitors since 2013 under a single-operator permit held by Oxalis, with the annual quota set with the national park at roughly 1,000 places. The cap is a conservation measure, and it is the reason the trip books out years ahead rather than a scarcity tactic.
Survey heritage
The company works with members of the British Cave Research Association expeditions that mapped Son Doong and much of the park, and its safety setup was built with those cavers involved.
Tu Lan and Tan Hoa
Oxalis opened the Tu Lan system near Tan Hoa village, about 70 km from Phong Nha town, and built its tourism around local employment. Tan Hoa was named a UN Tourism Best Tourism Village in 2023, with the Tu Lan operation central to that story.
Which caves they can take you into
Phong Nha works differently from most places. Routes are licensed cave by cave, usually to the company that did the survey work to open them, so you are rarely choosing between operators for the same trip. You are choosing a cave, and the cave decides the company.
Licensed to Oxalis Adventure
- Son Doong, the largest cave on earth
- Hang En, the third largest
- Hang Va and Nuoc Nut
- The Tu Lan system near Tan Hoa, including Hang Tien
Run by somebody else
- Kong Collapse, Hung Thoong, Tiger Cave series, Hang Pygmy, Victory Cave — Jungle Boss
- Paradise Cave, Phong Nha Cave, Dark Cave — Nobody: these are public ticketed sites you visit on your own
Every tour they run
3 tripsCheapest first, from 8,800,000 VND (about $340) to 79,500,000 VND (about $3,060).
Oxalis Adventure
Hang En Cave Adventure
2D1NTrek through jungle and river crossings to one of the largest cave chambers on earth, and camp on its sand beach beside a turquoise lake.
A night camped inside one of the largest cave chambers on earth, at the Son Doong expedition's own first campsite, for about a ninth of its price.
Oxalis Adventure
Hang Tien Exploration
4D3NFour days in the Tu Lan system near Tan Hoa: four caves, ladder descents on harnesses, cave swims, and two nights camped beside jade green lakes.
The largest dry cave of the Tu Lan system, in a different valley 70 km from Phong Nha that no other tour here touches.
Oxalis Adventure
Son Doong Cave Expedition
6D5NSix days to the largest cave on earth: jungle trek in via Hang En, three nights camped inside Son Doong, out over the 90 m Great Wall of Vietnam.
The largest known cave in the world, and this is the only tour licensed to enter it: roughly 1,000 permits a year, one operator.
Discount code
Discount coupon for their tours. Enter it at the payment step for 5% off.
Oxalis Adventure, questions worth asking
Is Oxalis the only way into Son Doong?
Yes. Son Doong runs under a single-operator permit held by Oxalis Adventure since tours began in 2013, capped at roughly 1,000 visitors a year as a conservation measure. There is no other legal route in, and any listing that suggests otherwise is selling something else.
How far ahead does Son Doong book out?
Typically one to two years for the season you want, and the season itself only runs January to August. If the wait rules it out, Hang En is run by the same company through the same valley and is the trip most people actually take: you camp inside a cave vast enough to hold a stadium, for about a ninth of the price.
Oxalis or Jungle Boss?
Usually not a real choice, because each cave here is licensed to exactly one company. Oxalis holds Son Doong, Hang En and the Tu Lan system; Jungle Boss holds Kong Collapse, Hung Thoong, the Tiger Cave series, Hang Pygmy and Victory Cave. Decide which cave you want and the operator follows. Both are established companies with strong safety records.
What do Oxalis tours cost?
The trips we list run from 8,800,000 VND for the two day Hang En Cave Adventure to 79,500,000 VND for the four day Son Doong Cave Expedition, with Hang Tien in the Tu Lan system between them. Prices include guides, safety staff, porters, meals and camping gear. Their own site is the source of truth and the place availability lives.
Where to go next
Facts on this page were taken from the operator's own site and public records in July 2026. We may earn a commission when you book through links here, at no extra cost to you, and it does not change what appears on this page.