Phong Nha-Ke Bang National Park is a UNESCO World Heritage Site located in Quang Binh province, near Nghe An. It is known for its stunning karst mountains, underground rivers, and extensive cave systems. Visitors can explore the park through guided tours, which include boat rides along the Son River and cave visits. The most famous cave in the park is Son Doong, the largest cave in the world. It offers a unique and unforgettable experience for adventure seekers and nature enthusiasts.