Hang Sơn Đoòng
Vietnam’s Hang Sơn Đoòng belongs to another world. Situated in Phong Nha-Ke Bang National Park, the cave’s main cavern is 650 feet high and three miles long. It is the world’s largest cave, and was only properly explored for the first time on record in 2009. It is amazing how such a massive structure could hide away for so long.
