Kaeng Sam Phan Bok

Kaeng Sam Phan Bok is the sandstone rock shelf on the Mekong at Ban Pong Pao, in Lao Ngam sub-district of Pho Sai district — the same landmark most people simply call “Sam Phan Bok,” meaning “three thousand holes.” This site and the Sam Phan Bok listing on this guide describe the identical formation; TAT catalogues them under two names, so treat the two pages as covering one place rather than separate stops.

The shelf itself spans more than 30 square kilometres of riverbed, though only the part above the waterline is walkable at any given time. Thousands of circular potholes — some barely a hand’s width, others deep enough to hold standing water year-round — have been carved into the reddish sandstone by centuries of swirling current. The formation only shows itself once the Mekong drops low enough, typically from December through May; outside that window most of it disappears back under the river.

Two ways to see it: walk the exposed rock directly, picking a route between the potholes and shallow pools, or take a longtail boat from Hat Salueng (Salueng Beach), which runs a roughly 4km, hour-long stretch along the river past the formation for around 1,000 THB per boat. The boat trip gives a wider view of the rock shelf’s scale from the water and works even when parts of the shelf are still partly submerged; walking gets you closer to the individual pothole textures. Local tour information is handled through the Song Khon sub-district administration office.

If you’re combining this with other Mekong-side stops, Ban Song Khon is a separate rock formation about 3km north with its own access point, and the wider trip usually pairs with Ubon Ratchathani city or Khong Chiam district further along the river.

Insider Tip: If you’ve already read up on “Sam Phan Bok” elsewhere and land on this page, you’re not missing a second attraction — book whichever access option (walking or boat) fits your schedule and skip researching it twice.

Watch out: the exposed rock is uneven and can be slick where water still pools — shoes with real grip matter more than the short distance from the car park suggests.