Andaman Sea Diving — Thailand's World-Class West Coast

The Andaman's dive sites cluster into several zones, each accessible from different bases.

Similan Islands (Islands 1–9): The core of Andaman diving. The western sides of the islands feature massive granite boulder fields with swim-throughs and caverns — Elephant Head Rock (Island 8) is the most famous, with boulders the size of houses creating a labyrinth of channels. The eastern sides offer gentle coral slopes ideal for less experienced divers. Manta rays visit the cleaning stations at Koh Bon (a separate island north of the main group) from January to April, with peak encounters in February and March.

Richelieu Rock: A submerged horseshoe-shaped pinnacle 18km east of the Surin Islands. The rock rises from 35+ meters to just below the surface and is covered in purple soft corals. It is Thailand's single most famous dive site, renowned for whale shark encounters (February–April), dense clouds of glassfish, seahorses, harlequin shrimp, and ornate ghost pipefish. Visibility ranges from 10 to 25 meters; currents can be significant.

Hin Daeng and Hin Muang: Twin deep-water pinnacles south of Koh Lanta, accessible by day trip from Koh Lanta or liveaboard from Phuket. Hin Daeng ('Red Rock') features a wall dropping from 10 to 60+ meters, draped in red soft corals. Hin Muang ('Purple Rock') is the deepest dive site in the area, with the pinnacle starting at 8 meters and the wall extending beyond 70 meters. Manta rays are frequently seen at both sites.

King Cruiser Wreck: A 85-meter car ferry that sank in 1997 between Phuket and Koh Phi Phi. Now resting at 12–32 meters, it has been extensively colonized by marine life and is Thailand's most accessible wreck dive. Suitable for Advanced Open Water divers.

Shark Point (Hin Musang): Three submerged limestone pinnacles covered in soft corals, barrel sponges, and leopard sharks resting on the sand at 18–22 meters. A reliable dive for macro enthusiasts and a regular stop on Phuket day trips.

The Andaman is best for intermediate to advanced divers seeking big marine life and varied topography. Liveaboard divers get the most value — accessing Richelieu Rock, Koh Bon, and the full Similan circuit. Day-trip divers from Phuket enjoy Shark Point, King Cruiser, and the Phi Phi area. Photographers rate Richelieu Rock among the world's best macro sites.

October–May, with the Similan National Park officially open November 1 – May 15. Peak conditions: January–April (best visibility, calmest seas, manta and whale shark season). October and November offer good diving but more variable conditions. June–September the west coast is affected by the southwest monsoon — most dive operators close, seas are rough, and the Similan park is closed.