A wonderful day to drive up north of Hue to Phong Nha Ke Bang National Park, The World Natural Heritage site. It is noted for its cave and grotto systems as it is composed of 300 caves and grottos. A 2009 survey brought the total discovered length of the cave system to about 126 km with many areas still not well explored. The Son Doong Cave which was discovered in the 2009 survey by British and Vietnamese explorers, is considered the largest cave in the world. Even before this discovery, Phong Nha held several world cave records, including the longest underground river as well as the largest combined caverns and passageways. It is just one and half an hour away from our hotel in Hue, we get to Dong Ha town, Quang Tri province. This province was a hottest spot during the American ad Vietnam War as it was in the DMZ area, hundred thousand ton of bombs dropping here. The bloodiest Quang Tri ancient citadel battle field, La Vang Church and Ben Hai River are a lively evident for this terrible war. On our arrival Phong Nha Ke Bang National Park, we enjoy our lunch at local restaurant then we take a boat trip to visit to Phong Nha Cave. Late afternoon we drive back to Hue via Ho Chi Minh Road then free at leisure.