Phong Nha Travel Guide 2026: Son Doong & the World’s Largest Cave Systems & Tips

Phong Nha, in central Vietnam, is the gateway to Phong Nha-Ke Bang National Park, a UNESCO World Heritage Site riddled with some of the world's largest cave systems, including Son Doong, the largest known cave on Earth. Boat trips through Phong Nha Cave itself are accessible to all visitors.