Similan Islands & Richelieu Rock


similan-and-surin-national-parks-1The name of the Similan Islands, located in the Andaman Sea, comes from a Malay word meaning nine (9) and refers to the original nine islands of the Mu Ko Similan National Park. The national park is now made up of two more islands: Koh Bon and Koh Tachai, which are located due northeast of Island 9 and are home to some of the best dive and snorkel sites in The Kingdom of Thailand.


The Similans has by far the best dive sites in Thailand and is often mentioned in journals and online polls as ranking among the top 10 dives sites in Southeast Asia as well as the rest of the world. The area offers something for every kind of diver from beginners taking their first open water dives along gentle slopping reefs to the more experienced who want to navigate their way around the stunning Richelieu Rock site. Visibility here can reach up to 40 meters, although normally it hovers around 25-30 meters, and your diving in Thailand trip can make you feel as if you’re in a giant aquarium.


During the dive season in the Similans (15 October – 15 May) the water is generally a barmy 28-29’C meaning that thin, shortie wetsuits can be worn giving you more flexibility when diving. Around the Similans and Richelieu Rock you will be treated to a variety of tropical fish and corals in an eclectic mix of colors, shapes and sizes, formidable rock formations, tunnels and intriguing crevices. Different types of rays, including mantas, turtles and sharks are regular visitors to the area offering our guests sometimes a great opportunity to view these magnificent creatures.



The Similan Islands are not only for diving and snorkeling they are a must see just for their pure beauty. Marveling at the large rainforests, taking a jungle trek and viewing the stunning rock formations (like at Donald Duck Bay) are just some of the active things you can do when visiting the island group. All the beaches are made from glorious powder-white sand that are gently lapped by crustal clear turquoise waters for you to dip in when it gets too hot.





similan-and-surin-national-parks-2Steaming ahead northeast from the Similans, you will reach Koh Bon after an hour and a half. This island is a fascinating rocky island with a scenic ridge stretching from the middle of the island down into the ocean. It offers no beaches or places to go ashore but compared to the Similan Islands, Koh Bon offers slightly more exotic and wild diving and snorkeling. This is also one of the best places to see the huge, placid and plankton-eating manta rays – beautiful and curious creatures that generally swim around for a long time. The manta’s often come close to the surface, providing snorkelers with the great opportunity to swim with them as well.






similan-and-surin-national-parks-3Travel another two hours north and you are at Koh Tachai – a desolate island with perhaps the most stunningly beautiful beach in the whole of the Andaman Sea. Just off the island, to the southeast, there are a couple of submerged plateaus with extremely colorful and exciting reefs, often visited by larger marine creatures and big swirling schools of barracudas. Closer to the island, just off the beach, snorkelers will find nice sloping reefs and many baby reef sharks. Our liveaboard, MV Oktavia, spends a full day at Koh Tachai: we are typically one of the only boats there and this is also where we dive the ‘Oktavia Corner’, which is our secret dive site that often gives us very pleasant surprises in the shape of several leopard sharks, eagle rays, reef sharks and on two occasions even whale sharks!





similan-and-surin-national-parks-4A two and a half hour cruise further north, about 18 kms east of the Surin Islands, you will reach the world famous underwater rock formation, Richelieu Rock. The rock consists of one main, horse shoe shaped splintered rock pinnacle, with several other smaller rocks around its edges. The site is totally submerged, except at low tide when the tip breaks the surface.


Richelieu Rock impressed even Jacques-Yves Cousteau with its stunning coral growth and spectacular marine life. Tiny critters such as harlequin shrimp and seahorses along with big schools of snapper and barracuda through to the largest fish in the ocean – the whale shark – has placed it as the best dive site in Thailand. As the entire surrounding area is just sandy bottomed, most of the marine life congregates against the rock and hence the variety and amount of marine life creatures is mind-blowing.


Richelieu Rock is part of the Mu Ko Surin National Park, which also covers the island and surrounding waters of the Surin Islands – a group of five islands, just a few kilometers south of the oceanic border with Myanmar. The islands are also home to two communities of the ethnic Moken minority, which belongs to the groups known as “Sea Gypsies”.


Both national parks (Similan and Surin) charge an entry and usage fee for guests entering the park(s). The generated income is used to further protect and preserve the natural resources of the parks. You will find the current fees in our price lists.

Similan Islands Islands Diving

Khao Lak Diving – Local Sites

Similan & Richelieu

Prices & Times