Koh Samui was one of the first islands to be discovered by foreign backpackers in the 1970s and today is among the most developed in Thailand, with a high-quality infrastructure. Direct flights from Bangkok, Singapore and Hong Kong serve its recently upgraded airport, and sophisticated hotels now outnumber the palm-leaf hut camps of previous eras. The real poster piece here, though, is Chaweng on the east coast – a 3-mile (5km) arc of heavenly white sand and crystalline water backed by coconut trees.