The tour through Son Doong Cave in Vietnam’s central province of Quang Binh has been listed among the top adventures in the world by British TV channel Dave.
The tour, which has been operated for only about a year, was ranked fifth among the 20 best tours after receiving 24 per cent of votes.
Son Doong is the only representative of Southeast Asia and one of few Asian destinations in the list.
The tour has beaten off competition from several well-known places such as Arctic Bay in Greenland and South Everest Base Camp in Nepal.
The cave was placed behind Mount Kilimanjaro in Tanzania, the Inca Trail leading to Machu Picchu in Peru, the Grand Canyon in the US and Thrihnukagigur Volcano in Iceland.
The British TV channel said that due to rugged terrain, visitors were required to register for a tour in advance.
Oxalis Adventure, the sole tour operator to the site, charges about $3,000 for a tour through Son Doong lasting for four days and three nights.
Since Son Doong Cave became an attractive tourist destination, the tours of the spectacular cave are almost booked up until 2021.
The report said only 20 tour slots remained available for 2019.
Not only in the forest and the cave, visitors can trek through 25km of mountain forest roads with uneven terrain, exploring about 9km of the cave. The tour includes the use of vines over rocky ascents.
Although foreign visitors make up a large number of tourists exploring the cave, the percentage of Vietnamese tourists has increased significantly, making up about a quarter in 2018.
The cave has been recognised as the largest in the world by three international organisations including Guinness (based in the UK), the Association World Record (based in Hong Kong) and World Kings (based in the US and India).
Located in the heart of Phong Nha-Ke Bang National Park in Quang Bình Province, it was discovered by a local in 1991 and was first explored in 2009 by a group of British scientists from the British Cave Research Association who conducted an extensive survey. It has been open to the public since 2013.
The 9km-long cave system, which extends through a mountain, was named one of the most captivating caves on earth by National Geographic.
Geologists say the cave formed two to five million years ago. It contains some of the tallest known stalagmites in the world, which are up to 70m high and is home to both a jungle and a river, whilst it could fit a 40-storey skyscraper inside.