Hin Nam No National Protected Area

Hin Nam No is a protected area in Khammouane Province that covers roughly 94,000 hectares of tropical rainforest, karst mountains, and over 200 caves. The terrain ranges from river valleys to rugged limestone walls that rise several hundred meters.

The area was officially declared a national protected zone in January 2020, after previously being managed as a regional protected zone. This decision marked a new focus on biodiversity preservation in the Mekong region.

The Xe Bang Fai River flows underground through the karst landscape and disappears below the surface at several points, where fishermen traditionally use boats to catch fish near certain cave entrances. Surrounding villages have relied for centuries on rice farming and the collection of forest products such as bamboo, resin, and wild honey.

Visitors must arrange permits and local guides through the administration office in Boualapha District before entering. The best time to visit is between November and March, when trails are drier and cave access is easier.

The Xe Bang Fai cave passage extends over 7 kilometers (4.3 miles) and ranks among the longest navigable underground rivers on Earth. During the dry season, boaters can travel deep into the chamber and see stalactites hanging directly above the water.