Even if you never strap on a dive tank, Koh Tao's beaches are worth the ferry ride. Sairee Beach on the west coast is the longest stretch of sand and the social hub, lined with bars and restaurants. Chalok Baan Kao in the south is quieter and good for swimming. For snorkelling, head to the rocky bays on the east side — Tanote Bay has coral close to shore.
In high season (December through March) accommodation fills up fast and prices climb. Visit in the shoulder months and you'll find better deals and fewer crowds. The island is small enough to explore by scooter in a day, though the inland roads are steep and rutted.