Namtok Saeng Chan (Long Ru)

One waterfall carries two names in the forest of Khong Chiam district: Namtok Saeng Chan (“moonlight”), for the silvery way its spray catches the light, and Namtok Long Ru (“through the hole”), for the roughly 2-metre opening the water pours through on its way down. Both describe the same 8-metre fall, part of Pha Taem National Park in Ubon Ratchathani province — not two separate cascades, whatever older write-ups claim.

The hole itself is the reason to come. Water carrying gravel and stones spun inside a shallow dip in the sandstone for years, slowly grinding it out until it perforated clean through the rock layer beneath — a natural drill working at geological speed. The Tha Long stream now drops through that opening onto the stone below, running fullest from July through January and thinning to a trickle in the dry months. Past the falls, a level walk across bare sandstone “stone plains” leads roughly a kilometre further to a cliff edge with views over the Mekong River — Khong Chiam district sits right on the river’s bend toward Laos, and wildflowers dot the stone flats here in season.

Getting to it means driving into Pha Taem National Park proper — this is a satellite site about 41 kilometres from the park headquarters, so it’s worth planning as its own half-day rather than a quick stop alongside the park’s famous 3,000-year-old cliff paintings. The standard park gate fee applies here as anywhere else inside the boundary.

Insider Tip: Go on or close to the full moon during the July-January flow season — the “moonlight” name isn’t just marketing, and the spray genuinely looks different under a full moon than on an ordinary night visit.

Watch out: The sandstone stone-plain walk to the cliff edge has no shade and can be slippery when wet from spray or rain — decent grip on your shoes matters more than speed here.