Sam Phan Bok

Sam Phan Bok is a natural rock formation on the Mekong River in Lao Ngam Subdistrict, Pho Sai District, Ubon Ratchathani Province, northeastern Thailand. Known as the Grand Canyon of Thailand, it features thousands of potholes and rock pools carved by river erosion. Visible only in the dry season when the Mekong water level recedes, it is notable for its unique sandstone landscape, seasonal pools and sunrise views over the Mekong.

Visitors can expect an expansive sandstone riverbed along the Mekong River exposed during the dry season, dotted with more than 3,000 potholes, basins, and rock pools of various shapes and sizes. The landscape includes eroded cliffs, sandy stretches, shallow pools, and viewpoints over the Mekong and the Laos bank. Areas can be explored on foot and by local boat tours. There are viewpoints for sunrise and photography, small food stalls and local guides near the parking area.

Sam Phan Bok is a geological formation created over thousands of years by the erosive force of the Mekong River on sandstone bedrock. The potholes were formed by swirling water and sediment abrasion during seasonal flooding, gradually carving the distinctive basins visible today when the river recedes in the dry season.

The site holds local significance along the Mekong River, which is central to Isan culture and livelihoods. Local folklore associates some rock pools with legends and natural beliefs, and the area is a well-known seasonal attraction for domestic visitors during the dry season.