Gateway to Phong Nha — the world's largest cave systems beneath jungle karst
Dong Hoi is a compact coastal city in Quảng Bình province — pleasant enough with a long beach and a French-era citadel, but its significance is as the base for Phong Nha-Kẻ Bàng National Park, a UNESCO World Heritage Site 50km to the west that contains some of the largest and most spectacular cave systems on Earth. Son Doong, discovered in 1991 and first explored in 2009, is the world's largest cave by volume — large enough to contain a 40-story building and its own localized weather system with cloud formation inside the chambers. Paradise Cave (Thiên Đường) is accessible without specialist…
Dong Hoi sat directly on the 17th Parallel — the ceasefire line that divided North and South Vietnam from 1954 to 1975 — making it one of the most heavily bombed cities in history during the Vietnam War. American bombing campaigns reduced the city to near-rubble; what visitors see today is almost entirely rebuilt since 1975. The Phong Nha cave system was used as a supply depot and hospital by North Vietnamese forces during the war, protecting soldiers from aerial bombardment. Phong Nha was first gazetted as a national park in 2001 and UNESCO-listed in 2003, primarily for its geological signif…