10 Beyond-Safari Adventures for the Bold Explorer

3. Descend Into Vietnam’s Son Doong Mega-Cave

The Son Doong Cave in Vietnam is one of the most extraordinary places on the planet—a cavern so immense it shelters its own jungles and weather systems. Guided expeditions descend into this subterranean marvel, navigating giant chambers, underground rivers, and surreal limestone formations. Entry is strictly regulated to protect the fragile ecosystem: only around 500 permits are granted each year. Most adventures start in Phong Nha, with connections from major Vietnamese cities and flights available from the US. These multi-day tours require moderate fitness and a spirit of adventure, but highly trained local teams ensure safety at every stage. Experts praise Son Doong as caving’s “final frontier,” with plenty of opportunities to spot rare flora and learn about conservation. Prime expedition season is February to August, and permits must be secured well in advance. For explorers who want a journey reserved for a select few, Son Doong delivers unmatched exclusivity and wonder beneath the earth.