The famed Son Dong cave, in the core of Phong Nha Ke Bang National Park which was recorded as the biggest cave in the world, was firstly named by Ho Khanh, the very first person known about its existence. Ho Khanh (or H? Khanh in Vietnamese) is the very first person over the world known about the cave since 1991. There are lots of untold stories about this man who has attached his life to the jungle