Hidden deep within Phong Nha-Ke Bang National Park, Son Doong Cave is the largest natural cave in the world and one of Vietnam’s most extraordinary natural wonders. Stretching over 9 kilometers in length and towering up to 200 meters high in some places, the cave houses its own jungle, underground river, and massive limestone formations.

Exploring Son Doong is not for the faint of heart – the expedition takes several days and requires good physical condition. But for those who venture inside, it offers a surreal, once-in-a-lifetime experience that feels like stepping into another world.