The special prize is a VND136 million (or US$6,000) expedition to Son Doong, the largest cave in the world, for two people.
The contest runs from July 1 to December 31. It was organized by the Management Board of the Phong Nha Ke Bang National Park to celebrate the 15th anniversary of the park's recognition as a World Natural Heritage site by UNESCO.
The contest is open to all Vietnamese people and foreigners aged 14 to 70, but not members of the Organizing Committee and related persons. The winners will be announced on January 1, 2019, and all of the prizes will be valid for two years from the date of the announcement.
The contest's questions are available in Vietnamese, English, and French.
