Phong Nha-Ke Bang National Park is situated in Quang Binh province. The Park can be compared to a huge and valuable geological museum of the world thanks to its complicated geological structure with different categories of stone including sandstone, quartz, schist, siliceous limestone... Phong Nha-Ke Bang Natural Park hides various myths of nature. It also has spectacular karst caves that look like splendid castles constituted underground karst millions years ago. Phong Nha-Ke Bang has around 300 caves and grottos of various sizes. Lying in the heart of Phong Nha-Ke Bang National Park, Son Doong, the world's largest natural cave, was discovered in 2009. The cave is seen as a valuable property of humanity with its aw-inspiring stalactites and stalagmites, splendid cave pearls and a primitive tropical forest.