Similan Islands

The Similan Islands are a group of granite islands in the Andaman Sea, off the west coast of Thailand. Huge boulders tumble from the islands into the sea, forming swim-throughs, arches and slopes covered in soft coral. The water is often very clear, and the islands are a national park.

The park has a short season. It is closed to visitors from about mid-May to mid-October, when the southwest monsoon makes the sea rough, and diving is only possible in the months between. Some sources and operators start trips later, in November, so confirm dates before you book an October trip. The most settled conditions usually run from November to April.

Most divers visit on a liveaboard from Phuket or Khao Lak, often combined with nearby sites further north. Day trips also run from Khao Lak. Most dive sites suit Open Water divers, and boats group divers by experience. A few exposed pinnacles can have strong current and are better left to Advanced divers.

Water temperature is usually 27 to 30°C, so a 3 mm suit is enough. Manta rays and, occasionally, whale sharks pass through during the season, but sightings vary from year to year. Some islands inside the park have been closed to protect the environment, so check which sites are open when you plan your route.