Son Doong Cave is currently the world’s largest cave and it is environmental sensitive therefore the Government of Quang Binh province issued a regulation that allows only 1000 tourists can visit the cave each year, each tour normally 10 tourists. In order to manage the cave sustainably, only one operator to be appointed to run tours to Son Doong and Oxalis Adventure was appointed as the only operator since 2013. Oxalis Adventure has been collaborating with the British Cave and Research Association in maintaining safety and conservation. Below are the reasons why Son Doong Expedition cost US$3000: (1)In this $3,000 tour price, 10 percent of tax is already included, $660 is the environmental service fee that will be transferred to the management of the Phong Nha – Ke Bang National Park. (2) The fees also go to the 22 porters, five safety assistants, one international tour guide, a cave expert, two cooks and a forest ranger who accompany every 10 people who take a tour. (3)Other expenses include transportation, hotel, food and drinks, management and administration during the tour. (Not including international and domestic airfares).