Hang Sơn Đoòng

Han Soon Doong - Mountain River Cave

Useful Information

Location:	Tân Trạch, Bố Trạch, Quảng Bình. 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. (17.4569440, 106.2875000)
Open:	After reservation. See online booking system. [2024]
Fee:	Adults VND 72,000,000 / USD 3,000. [2024]
Classification:	Karst Cave
Light:	bring torch
Dimension:	L=9,000 m, VR=150 m. . Main Passage: L=3,100 m, W=80 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. at Amazon.com
Address:	Hang Sơn Đoòng, Phong Nha-Ke Bang National Park, Son Trach, Bo Trach, Quang Binh, Viet Nam, Tel: +84-5236-77021, Fax: +84-5236-77021. E-mail:
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.

History

photography — Cave Bivouac extreme, Hang En. Public Domain.

1991	discovered by Hồ 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.

Description

Hang Sơn Đoòng (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, Showcave Gua Payau (Deer Cave) in Malaysia.

The cave is a very recent discovery, even for the locals. It was first discovered in 1991 by Hồ 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 Howard Limbert himself 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. And those are the only measures which are comparable. There is actually no official ranking for the floor size or the volume of caves, and that’s because we have no method to determine those values with the limited possibilities cavers have and the required accuracy. There are developments to do Laser scans in caves, but this is expensive, a lot of work, and the number of scanned caverns is still quite small.

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*10⁶m³. 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 heavy rains 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 considered the same passage.

This cave is one of the biggest caves of the world, but there are others which are comparable. It definitely has an enormous passage, with a length of more than 3 km, which is an enormous volume of underground space. The dolines are both big enough to be called tiankeng, there are few cave chambers which are as big as the wider sections of the passage. So it is definitely a cave of superlatives, and there are more. It has some of the largest stalagmites with a height of 70 m, and the most spectacular caves pearls "the size of baseballs". However, it’s stupid to simply call it the "largest" cave of the world.

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 at 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 through 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. The itinerary is simple: 9-hour walk to Hang En, bivouac, 2-hour walk to Son Doong, 7-hour caving, 2-hour walk back to Hang En, bivouac, 9-hour walk back. So there were three really exhausting days and only 7 hours for the visit of the cave. The tour was later extended to four days, with a second day and one bivouac in Son Doong Cave. And it costs USD 3,000 per person until today. The tours are nevertheless very popular and booked out for at least a year.

Those tours are offered by Oxalis Adventures, a new founded adventure trekking company. It offers currently [2024] 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 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. This is 10 years ago, and it was never built. It actually seems rather unlikely that it will ever be built.