Imagine you are lying on a boat adrift in a glittering, azure sea. Around you, the bay is formed by strangely shaped boulders, and, if you squint a little, you can see the shape of Donald Duck’s head, or the back of an elephant. Plunging into the water, you wander through magnificent coral gardens, or meander down streets of towering granite obelisks. Such are the Similan Islands at their best.

Universally recognized as world-class diving, the Similan Islands National Park lies some 100km or 4 hours from Phuket. The name, "Similan" comes from the Malay for nine, "sembilan", and there are nine granite islands. The islands are covered by lush rainforest, and against this backdrop, the white powder sand beaches stand out in stark contrast. It is common, here, to see sea-eagles fishing, and the sunsets can be fierily magnificent.

High season in this area officially begins in November, and ends in May, but the visibility varies all year round, from generally 20 metres to sometimes over 40 metres. On the west side of the islands, the granite has been eroded into massive blocks. Diving here, you explore swim-throughs, and little sun-lit grottoes, avoiding the huge sea fans, of course, and gazing at barracuda, cow-tail stingrays and feeding tuna. You may see a shy white-tip or black-tip shark, as they speed off into the blue. In good visibility, the granite boulders truly can seem like an underwater city. On the east side of the islands, you can drift through coral gardens and streams of fusiliers, watch dozens of featherworms pop closed as you pass, or observe fields of garden eels, swaying in the sand.

Of course, no trip to the Similans is complete without visiting the nearby Surin National Park. This is the site of the Richelieu Rock, world-famous for sightings of the magnificent, yet gentle, whale shark. Also, Ko Bon and Koh Tachai are top -class dives and are the best places to see manta rays.