Similan Islands
Thailand's Premier Marine Paradise with World-Class Dive Sites
The Similan Islands are a group of eleven granite islands in the Andaman Sea, approximately 70 kilometers off Thailand's west coast. Designated a national park in 1982, the islands are only accessible during the diving season from October to May, when the Andaman Sea is calm. The western sides of the islands feature dramatic granite boulder formations creating swim-throughs and caverns, while the eastern sides offer gentle coral slopes. The park's crown jewel is Richelieu Rock, a horseshoe-shaped submerged pinnacle that attracts whale sharks, manta rays, and an extraordinary density of marine life. Liveaboard trips of 2-5 days are the best way to explore the full range of sites, including the outlying Koh Bon and Koh Tachai.
Top Dive Sites
Richelieu Rock
5-35mWidely regarded as the best dive site in Thailand, this horseshoe-shaped submerged pinnacle rises from the deep and is completely covered in purple and red soft corals. The nutrient-rich waters attract whale sharks, manta rays, barracuda schools, and seahorses. Every crevice is packed with life from tiny frogfish to massive groupers.
Christmas Point
10-35mLocated on the northwestern tip of Similan Island 9, Christmas Point is a stunning landscape of massive granite boulders creating archways, swim-throughs, and caverns. Soft corals in every color drape the rocks, and leopard sharks, whitetip reef sharks, and octopuses are commonly seen.
Elephant Head Rock
10-30mNamed after a rock formation resembling an elephant's head, this site features a maze of massive underwater granite boulders forming exciting swim-throughs and channels. The strong currents bring in schools of trevally and fusiliers, and the deeper sections host leopard sharks and whitetip reef sharks.
North Point
10-30mThe northernmost dive site in the Similan Islands, North Point offers dramatic boulder formations with swim-throughs covered in colorful soft corals. The exposed location means strong currents that attract large pelagics including grey reef sharks, barracuda, and the occasional whale shark.
Tachai Reef (Tachai Pinnacle)
12-35mA submerged granite pinnacle rising to just 12 meters below the surface, Tachai Reef is a magnet for marine life. The pinnacle is covered in anemones, soft corals, and sea fans, attracting manta rays, whale sharks, leopard sharks, and huge schools of fusiliers and trevally.
Koh Bon
10-35mA small island south of the main Similan group, Koh Bon is renowned as one of the most reliable manta ray encounter sites in Thailand. The western ridge drops steeply and acts as a cleaning station where mantas come to be groomed. Currents can be strong, attracting large schools of barracuda and trevally.
Featured Marine Species
Whale Shark
Rhincodon typus
Manta Ray
Mobula alfredi
Leopard Shark
Stegostoma fasciatum
Ornate Ghost Pipefish
Solenostomus paradoxus
Giant Trevally
Caranx ignobilis
Harlequin Shrimp
Hymenocera picta
Diving Conditions
Best Season
October to May (national park open season; February to April for whale sharks)
Water Temperature
27-30°C
Visibility
15-40m
Difficulty
Beginner to Advanced
Frequently Asked Questions
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