National Geographic: The Worlds Biggest Cave
This week, Gray Line Halong Cruise would like to introduce the national geographic world biggest cave - Phong Nha Ke Bang, Quang Binh, Vietnam. Researchers have discovered 39 caves located deeply in Phong Nha, Ke Bang. Some of the caves still are mystery.
Track 0 trackers | Status: Ended | Airs on National Geographic |
- Season 1