Beijing-based photographer Ryan Deboodt (previously) recently returned from a trip to Laos where he spent two days exploring Tham Khoun Xe, one of the largest active river caves in the world. Stretching nearly 4.5 miles (7km) underground, the cave system is extraordinarily remote and Deboodt was permitted to photograph and film beyond where tourists are normally allowed to visit. The immensity of the subterranean space is staggering, with an average ceiling of almost 200 feet (60m) and width of 250 feet (76m) it’s hardly imaginable a space like this could exist underground.
Deboodt brought an arsenal of camera and video equipment as well as a drone to capture the expansive interiors of Tham Khoun Xe, much of which he edited into a short video included below. You can follow more of his cave photography from around the world on Facebook or Instagram, and read an interview about the endeavor on Smithsonian.