Depart from Hue for 3 hours to Phong Nha Cave. On the way, you will stop to visit some of the most famous battle-field in the Vietnam War, Ben Hai River, Hien Luong Bridge, lying in the Demilitarized Zone of the Vietnam War. Have lunch at a local restaurant then get on a boat and cruise along the river to Phong Nha Cave. The deeper one penetrates, the more magical are the natural aspects of the caves. After on boat for 700m, a large dry passage appears, then you can walk to discover the cave for 500m more. You will have a chance to explore the remain of Cham Altars and Inscriptions inside. Return to Hue in the late afternoon.