Located in the Um Phang Wildlife Sanctuary, this waterfall is Thailand’s largest, measuring an estimated 200m high and up to 400m wide during the rainy season. Thais, particularly fanatical about such things, consider Nam Tok Thilawsu to be the most beautiful waterfall in the country. There’s a shallow cave behind the falls and several levels of pools suitable for swimming.
The easy 2km path between the sanctuary headquarters and falls has been transformed into a self-guided nature tour. Surrounding the falls on both sides of the river are some of Thailand’s thickest stands of natural forest, and the hiking in the vicinity of Nam Tok Thilawsu can be superb. The forest here is said to contain more than 1300 varieties of palm; giant bamboo and strangler figs are also commonplace.
The best time to visit is from November to February (after the rainy season) when the 200m to 400m limestone cliffs alongside Mae Nam Klong are streaming with water and Nam Tok Thilawsu is at its wettest. In recent years, the access road to the sanctuary headquarters has been closed for part of the rainy season (June to September) to ease environmental damage. It's still possible to visit the waterfall at this time, but only by a three-hour raft trip, followed by a 30 minute 4WD trip to the sanctuary headquarters.
You can camp (30B) at the sanctuary headquarters, although you’ll have to bring your own tent, and it’s best to book ahead from November to January. This is also the only time of year the sanctuary’s basic restaurant is guaranteed to be open.
The vast majority of people visit the falls as part of an organised tour. A one-day tour from Um Phang starts at 2500B per person (minimum two people). It is possible to go independently, but no private transport is allowed into the sanctuary. If you’ve got your own wheels, take the turn-off to Rte 1167 just north of Um Phang. After 12km, turn left at the police checkpoint onto Rte 1288. Continue 6km until you reach the sanctuary checkpoint, where you pay the entry fee (200B). At this point you must park your vehicle and hire a sŏrng·tăa·ou (2000B) to take you the 25km to the sanctuary headquarters. Alternatively, you can take a Poeng Kloeng–bound sŏrng·tăa·ou to the sanctuary checkpoint (30B, hourly from 6.30am to 3.30pm).