Silver Beach (Crystal Bay)

Small, boulder-framed and almost absurdly photogenic, this is the cove everyone means when they talk about Samui's prettiest quick swim. Officially Haad Thong Ta-khian, unofficially Silver Beach or Crystal Bay, it tucks in between Chaweng and Lamai, a few hundred meters of pale sand, aquamarine water that stays clear over a sandy bottom, and granite boulders at each end that give the snorkeling its point. A handful of low-key resorts and restaurants back the sand, so an unplanned afternoon works fine here. Come early or late — it's small enough that a few dozen people change its character completely.