Hang Son Doong skyhole by John Spies. The Son Doong Cave in Vietnam is the biggest cave in the world. It's over miles long, has a jungle and river, and could fit a 40 story skyscraper within its walls. It was discovered by modern man 5 years ago.
Phong Nha-Ke Bang National Park, Vietnam - Jungle & Caves
The thick vegetation and hundreds of caves ensured Vietnam's Phong Nha-Ke Bang National Park a spot on the UNESCO World Heritage list. Here's my short introduction to some of the activities in Phong Nha - from the caves to the Botanical Garden amidst the