Koh Samui's coastline offers a beach for every mood. Chaweng is the longest and busiest — a wide strip of white sand backed by restaurants, bars, and shops. It's where the action is, for better or worse.
Lamai, the next beach south, is a step quieter with a more laid-back vibe and good swimming. Bophut on the north coast has a charming old fisherman's village at one end, with boutique hotels and low-key restaurants along the sand. Big Buddha Beach nearby is named for the 12-metre golden Buddha statue at its eastern end.
For real quiet, head to the less-developed south and west coasts. Taling Ngam and Lipa Noi see a fraction of the crowds and have some of the best sunset views on the island. Most beaches are swimmable year-round, though the Gulf side can get rough during the monsoon months of November and December.