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Heading for Ton Phet waterfall (น้ำตกโตนเพชร), Ranong, Thailand, there are a great many signboards indicating the direction required to take. Mostly at places where the direction is, in reality, so obvious.
However where they lead us to, is the start of a rutted track, where one should most probably continue upwards.

The car is ditched and the climb attacked. Fifteen minutes later, the climb comes to what was once a nice park-like setting with a view of the waterfall. The view of the waterfall on the opposite side of the valley!

Had one, though, taken a footpath along the river, before the climb, one would have easily reached the foot of the 11 levels of water gushing from the jungle to the partially developed valley.

The Ton Phet waterfall is just west off the Highway 4, heading south from Ranong town. The 2 km access road winds itself through rubber and palmoil plantations and the last stretch of road slowly deteriorates and becomes unsurfaced as it gets steeper. There’s a ford to cross after which you would have to make a decision, the fall proper or the view.

Unfortunately a simple internet search would have revealed

'Visitors are recommended to ask villagers in the area for directions'.

Cathy and Gary on vitualtourist report

'After lunch we headed for Ton Phet Waterfall, it took us ages to find this place, off the main road onto rough dirt tracks, talk about being out in the wilderness, I kept thinking what if we cant turn around at the end as in places the track was quite narrow.
Eventually we came to the end of the track and there was some sort of small waterfall with an old rickety falling down bridge going across the stream.
We didn’t stay here very long and decided to explore another little track off to the right, this track was a bit boggy so there was a little bit of sliding around.
At the end was a lovely swimming hole with a Thai family bathing, it was a great spot, perfect for a drink break'.

There is another photo on Panoramio.