The only option to visit the Son Doong cave is on four-day expeditions with Oxalis Adventure. It is rated as hard - adventure level 6 so one much have a good level of fitness and previous trekking experience.

On this expedition, one can expect multiple river crossings (surface and underground crossings), extensive rocky terrain, and multiple technical sections. One will have to be prepared to not see the sun for this time and live in perpetual darkness - there are 3 nights of camping underground.

Duration: 4 Day Expedition

Trekking Length: 17 Kilometers (10 Miles) Of Trekking Over Very Rocky Terrain

Caving Length: 8 Kilometers (5 Miles) Of Caving With Rope Climbs, Scrambling, At A 90 Meter Ascent of The Wall of Vietnam

Camping: 3 Nights of Underground Camping

Due to its environmental sensitivity, the Vietnamese authorities limit tourists to only 1,000 per year. Each tour is normally made up of 10 tourists. Only one tour operator (Oxalis Adventure) is permitted to run the expeditions into the cave and has been doing so since the cave first opened in 2013.

Limit: A Limit Of Only 1,000 Tourists Per Year

Tour Group: Normally 10 Tourists

Cost: $3,000

The cost of the expedition is $3,000. This includes a 10% tax and a $660 environmental service fee.

Also, included are 22 porters for the group, five safety assistants, one international tour guide, a cave expert, two cooks, and a forest ranger.

Oxalis Adventure also offers a range of other tours to other Vietnamese caves as well as many other attractions in the region with a full range of packages.

If one is unable to tour this gigantic cave, then one can still have a virtual tour with National Geographic's online tool.

Source: https://www.thetravel.com/visit-son-doong-the-worlds-largest-cave/