The first, you can see overview Phong Nha - Kẻ Bang at the pictuere at bellow:
Vietnam's Phong Nha-Ke Bang National Park is home to the world's largest cave -- a place few people have visited. Click through the gallery to see more images of this amazing underground world. This image shows how collapses caused by erosion leave openings through which incredible sunbeams penetrate, creating mesmerizing light shows.
From the second campsite inside Hang Son Doong visitors can stare out of an erosion hole (these are known as "dolines") and catch stars glistening on a clear night.
A strong crew of 20 porters, three guides, two caving experts, two chefs and two national park rangers assist on every expedition to Hang Son Doong. Just like the sherpas of Nepal it's the porters of Phong Nha who are the unsung heroes that make the adventure possible.
Inside Hang Son Doong
Inside Hang Son Doong
You can see the video of BBC of Son Dong - The best beautiful place!
Thanks you for your spend time, i will show more the best place in Vietnam in the next time, thanks so much!