Han Son Doong Cave is world's largest cave, located in Quang Binh province, Vietnam. It was found by a local man named Ho Khanh in 1991. The name "Son Doong" cave means "mountain river cave". It was created 2-5 million years ago by river water eroding away the limestone underneath the mountain where the limestone was weak, the ceiling collapsed creating huge skylights #fellaswim #vietnam