Located 50kms (31 mi) north of Dong Hoi, Phong Nha-Ke Bang National Park is one of the most truly awe-inspiring natural wonders of the world. Phong Nha cave in Phong Nha-Ke Bang National Park was once the world's largest natural cave system, with caverns large enough to house entire city blocks. Composed of over 300 caves and grottos, Phong Nha was measured at 126 known kms (78 mi) in length, with undoubtedly more yet to discover. Dong Hoi is the usual jump off spot to explore Phong Nha where many tour operators will provide a multitude of options to get you to and from your world class caving experience. Tour rides do come from both ends of the country to access Phong Kha so you can tie a visit into a longer ride from Vinh or Hue.

Don’t get caught only exploring Phong Nha where there are 300 other caves to explore. In 2009, researchers from both England and Vietnam discovered Son Doong cave, and it is somewhat open to tourism with a limited number of entrance passes being issued every year. Both caves are home to underground rivers and have pools to swim in. Surprisingly enough, the best way to explore Phong Nha is by boat. You can hire a boat down river, or your tour agency will arrange a boat ride for you; however, a short 5km (3.1 mi) jungle hike will also get you to the cavern.

Another worthwhile venture in Phong Nha-Ke Bang National Park is the Nuoc Mooc eco-trail. This nature trail will take you through scenic riverside vistas and across multiple handmade bamboo bridges. The eco-trail allows you multiple places to stop and swim. This trail is relatively new and is a sign of where eco-tourism in the area is heading. Most tours in the region will end up at Phong Nha-Ke Bang National Park, so bring your headlamp and be prepared for some world class spelunking!