Ranong is a seaside town (on the Andaman coast), on the frontier with Myanmar.
My suggestion
If you are going to the little island of Koh Chang (not to be confused with the big one which is on the east of Thailand), check the weather forecast, otherwise you might find yourself stuck on the island without a boat...
The Khong Chiam region is still largely unaffected by tourism and, for those willing to explore it, offers spectacular scenery and the promise of peaceful days spent well away from the noise and chaos of the urban environment. With its waterfalls, cliffs and rock paintings, Pha Taem is the kind of place you simply never tire of exploring.