08°39′N 97°38′ESIMILAN ISLANDS, ANDAMAN SEA
Similan Islands, Thailand.
Granite boulders, white-sand channels, and the clearest water in the Andaman — a national park that closes half the year so it can stay this way.
Why the diving world rates it.
The Similans are a chain of granite islands whose underwater landscape matches the postcard above: enormous boulders stacked into swim-throughs and canyons, white sand glowing at depth, and visibility the Andaman is famous for. To the north sits Richelieu Rock — routinely named among the world's best dive sites — where whale sharks and mantas pass in season. The whole area is a national park, closed from mid-May to mid-October, which is exactly why it stays exceptional.
Why we chose it.
The season structure suits designed trips: when the park opens in October, conditions are at their best and the diving can be taken as day boats from the coast or as a liveaboard — whichever suits the party. Phuket's connections make it one of the easiest world-class destinations in Asia to reach, and courses at every level run beautifully here.
Good to know.
Season mid-October to mid-May. Day-boat and liveaboard formats. International connections via Phuket.