Oxalis, the only private company licensed to explore Son Doong, got the nod from Quang Binh Province authorities to escort tourists through the cave from now till 2030. Earlier, the license was only bestowed annually.   

Quang Binh requires the tour operator to achieve economic efficiency and ensure tourist safety while promoting Son Doong, a fast emerging tourist destination.

Nguyen Chau A, General Director of Oxalis, said long-term permission would help the company plan tours and take advantage of promotional opportunities.

Howard Limbert, former head of British Caving Association, and his wife Deb spent nearly 13 years surveying caves in Vietnam. In 2009, they concluded an initial exploration and declared Son Doong the world's largest cave.

Visitors make an expedition into Pygmy Cave deep in Vietnam’s world-renowned
cave kingdom in Phong Nha-Ke Bang National Park, Quang Binh Province.
Photo by VnExpress/Hoang Tao.

Son Doong opened to tourists in 2013 with the five kilometer-long system, 150 meters high and 200 meters wide, containing at least 150 individual caves, a dense subterranean jungle and several underground rivers.

Due to limited space, registration for Son Doong tours must be made well in advance. According to Oxalis, only 300 slots are available this year.

A four-day expedition costs $3,000, with buses running from Hanoi to Dong Hoi, capital of Quang Binh, and then to the park.

Quang Binh’s government recently increased the number of tourists allowed to visit the cave in a year from 640 to 900.

Earlier this year, the U.K.-based travel guide publisher, Lonely Planet, named Son Doong Cave among the best places to visit in 2019.

In Britain, a Son Doong expedition was among the greatest adventures ever, according to British TV channel Dave, a panel of travel experts and editors of U.K. tabloid Daily Mail that polled 2,000 people aged 40 or under last September.

CNN in September said exploring the world’s largest cave, eating pho in Hanoi and cruising down the Mekong Delta are among the 13 most memorable experiences in Vietnam.