Namtok Sai Rung

Namtok Sai Rung drops around 100 metres off a limestone cliff inside Khao Banthat Wildlife Sanctuary, in Yan Ta Khao district, Trang. It’s a single main fall that breaks into a few smaller ledges near the base, and — unlike many of the smaller waterfalls scattered around the province — it keeps flowing year-round.

The “rainbow” in the name is a real, specific effect rather than marketing: spray thrown up by the drop catches the sun at the right angle and forms a visible rainbow in the mist, typically somewhere between 11:00 and 16:00 on a clear day. Turn up early morning or under cloud cover and there’s a good chance you won’t see it at all — timing the visit around midday is worth doing if that’s the reason you’re going.

It sits inside a wildlife sanctuary rather than a national park, which is a meaningful difference: paths are less developed than at Thailand’s better-known waterfall parks, and the surrounding forest is protected habitat rather than a landscaped visitor area. A walk from the car park at Na Chum Het brings you to the falls — accounts of the exact distance vary from a few hundred metres to just over a kilometre depending on which entrance you use — and there’s a pool at the base where swimming is possible, with cool water that holds up even through the hot season.

Khao Banthat Wildlife Sanctuary itself spans a large stretch of mountain forest across Trang, Phatthalung, Satun and Songkhla provinces, and Sai Rung is one of several waterfalls tucked into its Trang side. That scale is part of why the area stays quieter than Trang’s more heavily promoted waterfalls — there’s simply more forest to spread visitors across.

Insider Tip: If seeing the rainbow effect matters to you, go on a sunny day and aim to be at the falls around midday to early afternoon — overcast skies or a late-afternoon visit will likely mean no rainbow, even though the waterfall itself still runs.

Watch out: This is a wildlife sanctuary, not a manicured park — there are no food stalls or facilities at the site, so bring water and snacks. Stick to the marked path rather than wandering into the surrounding forest.

Two more Yan Ta Khao district waterfalls sit within easy reach if you want to make a day of it: Namtok Phrai Sawan and Namtok Lam Plok. For more on the area, see the Trang destination guide.