Americans booked the majority of permits with the number of pax of 145 people. Followings are Australians and Vietnamese with total adventurers of 123 and 115, respectively.

Inside Son Doong Cave - Quang Binh Vietnam central tour
The sun shines into Son Doong cave

Belonging to the Central province of Quang Binh, Son Doong cave was firstly discovered by a local man in 1991. However, it has been made public by the United Kingdom’s Royal Geographical Society since 2009. Up to now, Son Doong Cave is acknowledged as the biggest cave all over the world.

It is measured that the cave of Son Doong is about 200 metres wide and more than 150 metres high. Thanks to its 250-meter-tall chamber, Son Doong can be said to have enough space to accommodate a 40-storey skyscraper.

There are at least 150 individual grottos, a dense subterranean jungle, and several underground rivers inside Son Doong Cave.

Son Doong has been proudly appeared in prestigious magazines and on television channels of the National Geographic in 2011 and recently on the American Broadcasting Company channel.

According to the local government, Oxalis Adventure Tours is permitted to organize Quang Binh tour to explore the Son Doong. The cost for each tour is 3,000 USD per pax. In addition, the number of tourists is strictly limited at 500 passengers.

Until now, it is reported that 250 adventurous travelers have explored the Cave so far this year.