Krabi

Railay is not an island, though it behaves like one: the cliffs cut it off from the road, so you arrive by longtail from Ao Nang or Krabi Town for ฿100 to ฿200. That crossing is what keeps it quieter than the mainland beaches, and it is also what strands you when the sea gets up.

The weather decides this trip more than anything else. Between roughly November and March the Andaman side is dry with calm water and reliable boats. From May the southwest monsoon brings swell and rain, some operators stop running, and a booked island night becomes a night you cannot reach. If your dates fall in the wet half, look at the Gulf coast instead — the two sides do not fail at the same time.

Costs sit above the national average here, mostly because the beach is a captive market. A dorm bed is still ฿400 to ฿700, but a decent sea-view room in January is a different order of money, and everything eaten within sight of the sand carries a premium. Walk inland for food and the numbers come back down to the rest of the country.