Exclusive adventure tours taking visitors into Son Doong cave, the largest cave in the world located in Quang Binh province, are fully booked for the entirety of the year ahead.

1,000 visitors have signed up to participate in tours throughout the year, with only five registering for tours in August before the rainy season starts in QuangBinh province and trips are unable to run.

Each year the province permits a maximum of 1,000 visitors to enter Son Doong cave, with each tour consisting of a maximum of 10 visitors who explore 30km over the course of four days and three nights.

Source: VNA