A good place to climb for beginners, with all routes in the 5.6-5.9 range. (Thailand uses the French rating system, so that's 5-6a)
From the right end of Ton Sai beach (looking out to the sea) where the boat channel is located, walk up the dirt road. Walk pass the generator and Lost Wall is on the left. If you find yourself in the Monkey Wall area, you've walked too far.