If you're ready for a serious case of wanderlust, watch this footage from what the British Cave Research Association believes to be the world's largest cave. Located in Vietnam's Annamite Mountains, Hang Son Doong (meaning mountain river cave) is nearly six miles long. Formed by an underground river that slowly carved its way through mountain limestone, there are caverns within Hang Son Doong large enough to house an entire New York City block — and some that could even hold skyscrapers stretching 40-stories high.
While most caves are damp, dark places where little life exists, there's a nearly 3-kilometer section of Hang Son Doong where the roof has caved in. The result is a full-fledged rainforest growing within the cave.
Hang Son Doong was discovered by a local in 1991, but it wasn't fully explored until 2010. British husband and wife team Howard and Deb Limbert first attempted to navigate the cave in 2009, but were stopped a few miles in by a 200-foot wall they weren't equipped to scale. The next year they successfully navigated the entire space.
Hang Son Doong sits within Phong Nha-Ke Bang National Park, a 300-square mile site on Vietnam's border with Laos. It's believed that there are more than 300 caves and grottos within the park's boundaries — many of which are still undiscovered. The park was named a World Heritage Site in 2003 due to its incredible network of caves.
Beijing-based photographer Ryan Deboodt shot the six-minute-long video using a GoPro Hero 4 attached to a DJI Phantom 2 drone. Deboodt specializes in cave and adventure photography and has captured images in many of Vietnam's most spectacular caverns. "It's incredibly difficult to put into words how amazing Hang Son Doong really is. From the shear size of the cave to the two doline where plant life has started growing inside the cave. It is truly otherworldly and something that probably can't be experienced anywhere else in the world," wrote Deboodt on his blog after a 2014 expedition.