The origin of Nan River naer Bo Klua
There are signs along route 1081 (north of Bo Klua) and there is a parking. From there you will have to walk into the jungle.
Now they say it is only 200m walking and I am sure indeed you will hit the Nan River, but looking on satellite images the real origin is a bit further from the road. No I did not walk all the way. A bit too slippery for me. #NanProvince