Ulu Slim Hot Spring

What you will see

The spring feeds four small natural pools. The heat comes from granite that has been cooling slowly since the Triassic, not from a volcano, and local guides say that is why there is little sulphur smell. Green moss and heat-loving microbes grow at the edges of the hot water. A single information board explains the geology.

The 92°C figure is from the 1997 national inventory. The 104°C quoted by travel sites and a local operator has not appeared in any scientific source.

Safety

Water at the source is close to boiling and scalds on contact. There are no barriers between the path and the pools, the ground stays wet from the outflow, and there is no first aid on site. Keep children within arm's reach. Some visitors boil eggs here by lowering them in a container on a string; never put your hand in.

Facilities and condition

A walkway now leads to the springs, with a gazebo along the way, and a December 2025 reviewer noted a small parking area where cars can turn around. There are still no toilets, changing rooms, surau, food or drinking water. Entry is free and there are no fixed hours. A 2015 visitor was glad it had stayed a natural pond instead of being cemented over, and a July 2024 report found the site reachable with the information board intact.

Upkeep has slipped since. Reviewers in March and June 2026 say cattle are allowed to wander in, and the area around the pools is fouled with dung that mixes with the smell of the spring. Watch where you step. Some parts of the village have no mobile signal.

Why scientists care

Ulu Slim Hot Spring keeps coming up in Malaysian geothermal research. A 2017 USM study named it one of five priority sites in Peninsular Malaysia for future geothermal energy, and a 2025 review listed it among four localities with recognised potential, noting a magnetotelluric survey there. In October 2025, UKM spin-off Geothermal Resources Sdn Bhd held International Geothermal Week Malaysia at Ulu Slim, and UKM spoke of an Ulu Slim Geothermal Research Centre.

Pos Bersih warm spring

A second, much cooler spring at Pos Bersih, an Orang Asli settlement about 4 km north of Ulu Slim, was recorded at 36°C in 1997. Researchers treat it as sharing a source with the Ulu Slim springs. There is no visitor information for it.

Combine it with

Local operators around Slim River sell full-day rafting, trekking and waterfall packages. If you actually want to soak, Sungai Klah Hot Springs near Sungkai is the nearest developed park.