Phong Nha–Kẻ Bàng is a national park and UNESCO World Heritage site. It’s one of the largest karst areas in the world; the unique topography and extensive cave system were created over time as water eroded the limestone formations. It has only recently become a tourist destination, as some of its most impressive caves (including Son Doong, the largest cave in the world) were just discovered in the early 21st century.
On our first day in Phong Nha we explored Paradise Cave. Paradise is one of the most accessible caves in the area and is a popular destination for tourists. Its dramatically lit formations were an awe-inspiring introduction to the subterranean environment of Phong Nha. The cave has a wooden walkway installed for about 1 kilometer, but guided tours can venture much deeper into the vast 7-or-so kilometer long system.