Hang Son Doong

Han Soon Doong - Mountain River Cave

Useful Information

Location: Phong Nha - Ke Bang tourist complex, Quang Binh province. Binh Lu Commune, Phong Tho District. Near Hue, 50 km northwest of Dong Hoi. 500 km south of the capital, Hanoi.
Open: All year after appointment, weather permitting.
Sep to May recommended.
Fee: Per person USD 750.
Classification: SpeleologyKarst cave
Light: bring torch
Dimension: L=7,300 m. Main Passage: L=3,100 m, W=m, H=180 m. Biggest chamber: W=175 m, H=350 m.
Guided tours:
Photography: allowed
Accessibility: no
Bibliography: [LIM2016] H. Limbert, D. Limbert, N. Hieu, V. V. Phái, D. Kinh Bac, T. H. Phuong, D. Granger (2016): The discovery and exploration of Hang Son Doong. Boletín Geológico y Minero, 127 (1): 165-176, ISSN: 0366-0176
National Geographic (2011): World's Biggest Cave. DVD, NTSC, English, 45 minutes. This is the cave documentary by the National Geographic Society on DVD, the photography has the high quality we are used to from the National Geographic Society. Worldat Amazon.com
Address: Hang Son Doong, Phong Nha-Ke Bang National Park, Son Trach, Bo Trach, Quang Binh, Viet Nam, Tel: +84-5236-77021, Fax: +84-5236-77021. E-mail: contact
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
Please check rates and details directly with the companies in question if you need more recent info.


Cave Bivouac extreme, Hang En. Public Domain.
1991 discovered by Ho Khanh from Phong Nha village.
2009 first explored by British Cavers.
AUG-2013 cave trekking tours run by Oxalis Company.
AUG-2014 cave trekking tours stopped.
2014 permission to build a US$212-million cable car system inside the cave.
JAN-2015 cave trekking tours restarted with 500 permits.


Hang Son Doong, Vietnam. Public Domain.
Hang Son Doong, Vietnam. Public Domain.

Hang Son Doong (Mountain River Cave) is the world's "largest cave passage". The huge main passage is 180 m high, 80 m wide and 3.1 km long, some parts of the passage are even 175 m wide at the bottom. This makes it (probably) a little bigger than the former first, ShowcaveGua Payau (Deer Cave) in Malaysia.

The cave is a very recent discovery, even for the locals. It was first discovered in 1991 by Ho Khanh from Phong Nha village. But the locals never entered the cave, because the entrance emitted a frightful wind and noise. Or because the first thing in the cave was a 70 m deep drop. He then worked as a guide for a British caving team and showed them the entrance on their 2009 expedition. The British cavers entered the rather small entrance, at least under Vietnamese conditions, which is "only" 10 m high and 30 m wide. After the entrance the passage opened and was 180 m high and 80 m wide. In the first year they surveyed 6.5 km of the huge passage, without reaching the end. The team had to return the next year to complete the survey of this cave.

After the trip report was published the cave soon became known as the biggest cave of the world or the largest cave of the world. Actually both are stupid terms, as it does not explain in which sense it is biggest. And the bigger the cave, the lower the accuracy, as H. Limbert wrote in [LIM2016]: "accurate measurements of cave passages become very difficult when the caves are so large". Hang Son Doong is 7.3 km long, Mammoth Cave in the U.S.A. is 590 km long, so it is not the longest cave. The same applies for the vertical range. There is actually no official ranking for the volume of caves, and that's because it makes no sense. It makes no sense because we have no method to determine the volume.

Actually Howard Limbert published a volume he "surveyed" of 38.4*106m³ (Wikipedia). As this is a guesstimate you should probably add something like ±20*106. He has the opinion that Hang Son Dong is bigger than Deer Cave, but it is still only his opinion. Nevertheless, the journalists who published articles afterwards were too stupid to copy/paste, so we even found an article which tells us the cave has a size of 38.4*106 m. 106 is one million, not 106. So don't believe the multiple publications.

Between the two main exits there are two sections with a collapsed ceiling. The debris from the collapse blocks the passage and forms a huge dam. The first is called Watch Out For Dinosaurs and contains an impressive waterfall, which flows only after a rain during dry season. The largest doline is 175 m wide and 350 m high and was named Garden of Edam. There is a patch of jungle on the floor which gets enough light because of the enormous size of the doline. By the way, this has a massive influence on the size: two passages on opposite sides of dolines are generally not the same passage.

The cave is accessible only during dry season. During monsoon the huge passage fills with water and becomes a crushing river. The watermarks are visible high up the walls.

Many people obviously think the cave was open to visitors, because its discovery was published widely. There are publications with glossy pictures, which produce the wish to see it with ones own eyes. But the cave is not developed as a show cave and not really suitable for semi-wild tours. There are numerous difficult and dangerous sections which require experience and special equipment. And actually it is located in Phong Nha-Ke Bang National Park and so it is protected by law. The best way to see the cave is on the great pictures of the National Geographic Society.

Nevertheless the cave was first opened on demanding three day caving tours run by local guides in 2013. The cave entrance in the middle of the National Park is reached after an arduous nine-hour trek trough dense jungle. It is almost impossible to find without a guide. The two nights are spent in En Cave, about two hours from Hang Son. So there was one day with about 7 hours for the exploration of the cave. And it cost USD 3000 per person.

Those tours are offered by Oxalis Adventures, a new founded adventure trekking company. It offers currently [2019] four different tour sizes, from one to four days, into various caves. The caves are Son Doong Cave, Hang En Cave, Hang Va Cave, Hang Tien Cave, Nuoc Nut Cave, and Tu Lan Cave System. All caves are located in Phong Nha-Ke Bang National Park. Over 500 locals from Phong Nha are employed by Oxalis. They are actually an important employer in this area, giving work to formerly unemployed locals who made their living as illegal loggers and hunters in the National Park. With the participation of cave experts of the British Cave and Research Association (BCRA), namely Howard Limbert, the safety of the tours is quite good. The equipment is of high quality and the guides are well educated.

The local resort developer Sun Group from Da Nang City has received the permission to build a USD 212-million cable car system inside the cave in 2014. The 10.6 km long cable car would have four sections and connect a planned resort complex with the caves Dong Tien Son and Hang Son Dong. So far it is not clear when and if this cable car will be built. It actually seems rather unlikely that it will ever be built.