This group of rocks and islands lies 90 minutes by speedboat off the coast of Phang-Nga, or eight or more hours by slow boat from Phuket. The area was declared a marine national park in 1982 and consequently remains largely undeveloped. Derived from the Malay term sembilan, meaning 'nine', Similan refers to the nine main islands in the group.
The waters surrounding the Similans are teeming with tropical fish, colourful coral, and offer exceptional underwater visibility. As a result, the diving is generally considered to be the best in the region, and compares favourably with some of the best in the world. (see more about diving here).
Part of the reason for this is the very interesting submarine topography, due in part to the huge granite boulders which not only litter the shorelines, but also lie in jumbled heaps beneath the waves to depths of 35 metres and beyond.