The Similan Islands, also known as Koh Similan National Park and The Similan Archipelago, contain Thailand's best dive sites. The area is located quite far (60km) from Thailand's west coast, thus providing total isolation for those on scuba diving holidays from the hustle and bustle of the mainland, Phuket and Koh Phi Phi. Also, being right out in the Andaman Sea, the water is both clean and full of nutrients brought up from deeper and cooler waters in the Indian Ocean. These nutrients supply food for the marine life.

This set of nine main islands and more than twenty world-class dive sites really is the perfect place to enjoy the scuba diving Thailand has to offer. There is one drawback, though. Once you have dived the Similan Islands, you will always compare the experience to other dive locations in Thailand and around the world. A little like driving a Rolls Royce; nothing else will ever be as good.

From Koh Huyong (island 1) in the south to Koh Bangu in the north there is a wonderful selection of dive sites for PADI diving, pristine beaches and snorkelling areas. Further north and north-east are Koh Surin and Richelieu Rock. The latter was described by Jacques Cousteau as one of the best dive sites in the world. Although some people like to include Koh Surin and Richelieu Rock when describing the Similan Islands, technically they are separate.

One must research and be prepared for PADI scuba diving in the Similan Islands. For the months between May and October (inc.) the whole area is often closed. In fact, the Thai government has recently toyed with the idea of completely shutting down the whole national park to allow the marine environment recover from over fishing, coral bleaching and the tsunami. In addition, not just anyone can go and dive there. Firstly, there is a small fee that must be paid to enter the national park, and secondly, the diving conditions can be a bit much for inexperienced divers. Those having taken a few scuba diving lessons and just graduated from a PADI Open Water course are probably not experienced enough to tackle the depths and currents of the best Similan dive sites. Saying that though, there are plenty of places there for gentler diving.

What can be seen underwater at the Similans?

There are so many different marine creatures, that it's difficult to know where to start. Whale Sharks (Rhincodon Typus) are usually at the top of most people's list, and can be seen year round, but more so in the Thai summer (March-June). Other big fish such as Manta Rays (Manta Birostris) and Devil Rays (Mobula Mobular) are common visitors to the dive sites. Marine mammals, such as whales and dolphins, are unlikely to be met by divers underwater, but can sometimes be seen breaching the surface (jumping) from whichever boat you are on. There are also several other kinds of cartilaginous fishes (sharks and rays) such as Leopard/Zebra Sharks (Stegostoma Fasciatum), White Tip Reef Sharks (Triaenodon Obesus), and the Shovel Nose Ray/Guitar Shark (Rhinobatos Productus) just to name a few. In addition to the bigger stuff, divers can see a huge selection of hard and soft corals, as well as tiny but interesting marine life such as nudibranchs and sea horses. Mid-size fish and mollusks are also hugely popular. Moray eels (more than a dozen species), octopuses, barracuda, sweet lips, and many other colourful or interesting animals can be seen in the Similans. Click on our list of Similan dive sites to get more specific and detailed information on what to expect at each location.

Getting to the Similan Islands is possible via a number of forms of transport from a selection of starting points on the mainland. The most popular is taking a liveaboard and staying out at sea for three days to a week. These trips usually try to visit all the best sites on the Similans, as well as popping over to Koh Surin and Richelieu Rock if conditions allow. Families with members who don't dive often take proper cruises around the islands, stopping at secluded beaches and snorkeling sites. Alternatively, there are day trips for those who either don't have time to spend days out at sea, or who don't like sleeping on boats. These day trips can be on a regular dive boat or speedboat. However, one must appreciate the length of time travelling, plus extended surface intervals. It's going to be a very long two-dive or three-dive day.

As far as dive centres go, there are none on the Similans, as there is very little accommodation or shops. Most divers choose to book up with a PADI IDC centre on Phuket or in Ranong to take care of their needs.