The smell of coffee fills the warm, humid tropical air. Before a cave in the rainforest, some men have heated water in a bamboo tube over an open fire and then prepared a jet-black brew. This isn’t only for the tourists, but is a tradition in southern Thailand. The drink is served likewise from cups made of bamboo. Sipping their coffee, the visitors look out on the Sok River, where the rafts on which they came are bobbing peacefully. Cherry-red dragonflies buzz above the water, an army of ants marches across the sandy soil, and high up in the tree is the sound of exotic birds singing away. One…