Get picked up for your hotel and begin heading for the Quang Binh province, which the Phong Nha Ke Bang National Park extends into. On the way, visit the Vietnamese Demilitarized Zone, which runs along the Ben Hai River and once divided North and South Vietnam. Learn about its role in during the Vietnam War, and hear stories about the violent battles which took place on the river and Hien Luong Bridge from your guide. After arriving in Quang Binh, grab lunch at a local restaurant before exploring the caves of Phong Nha Ke Bang National Park. Your guide takes you on a boat up the Son River to the Phong Nha Cave, which runs over 27 miles (44.5 km) long. Inside, marvel at its underground river and incredible rock formations, which are illuminated by colorful lights. Also get the chance to visit the Tien Son Cave, a cavernous space rife with impressive speleothems. At the end of the day, enjoy overnight accommodation at a hotel in Phong Nha