Guide to diving the Similan Islands

The Similan Islands are the best diving location in Thailand. There are over 25 dive sites surrounded by 9 paradise islands. The dramatic underwater topography varies from stacks of giant granite boulders, pinnacles, and gently sloping coral reefs. Visibility can be up to 30 metres with sea temperatures of around 29°C.

The Similan Islands are a group of 9 islands located in the Andaman Sea 70km off the coast of Phang Nga province in southern Thailand. The islands were made into a national marine park in 1982 and named Mu Ko Similan National Marine Park. In 1998 2 more islands slightly further to the north called Koh Bon and Koh Tachai were added to the park. Thailand’s best dive site Richelieu Rock is also accessible from the Similan islands and is included in most liveaboard trips to the islands.

similan islands diving blogA scuba diving liveaboard entering Donald Duck Bay, island No.8

The word “Similan” means 9 in Yawi language. Yawi was spoken in the past by Thai’s with Malaysian decent who were settled in the south of Thailand. The islands all have Yawi names but for simplicity they are now referred to as numbers 1-9. The islands are numbered from south to north, island no.1 being the furthest south and island no.9 being the furthest north. Similan Islands 1,2, and 3 are not open to the public as there has been a long running turtle hatching protection program in place, along with efforts to conserve the coral reefs.

Similan Islands Dive Sites

Check out our google map for information on all of the Similan islands dive sites including photo’s, descriptions, and dive site plans.


When To Dive The Similan Islands

The Similan Islands are officially open for scuba diving every year from the middle of October to the middle of May. At all other times the park is closed due to high winds during the monsoon season. Conditions during the dive season are excellent with calm seas, up to 30 metres underwater visibility, and sea temperatures hanging around 29°C.

Similan Islands Liveaboards

If you have time, by far the best option to dive at the Similan Islands is by diving on a liveaboard. Standard liveaboard trips run for 4 days with 14 dives, shorter or longer trips are also available for anything from 2-7 days. Liveaboards allow you to fully relax and take in the scenery at the islands both above and below the water. On a liveaboard you dive, eat, and sleep on board, making new friends with like minded people from all around the world.

Dive, eat , sleep, repeat on a Similan Islands liveaboard

4 Day liveaboard trips can cost anything from 15,000 Baht to 40,000+ Baht, as with most things you get what you pay for. On lower cost boats you will get no frills service and shared accommodation, on more expensive boats you will get 5 star service, and luxury accommodation with queen sized beds and en-suite bathrooms. If you spend around 25,000 Baht you should be able to get a comfortable mid range liveaboard with good service and private cabins. Mid range liveaboards are more than adequate for most divers.

mv aquatic liveaboard master cabinMaster Suite on MV Aquatic, a comfortable mid-range Similan liveaboard

Flexible Liveaboards

Overnight or flexible liveaboards are great for those who have limited time but still want to sample the great dive sites at the Similan Islands. Throughout most dive seasons, there are a few boats which are permanently stationed at the islands running a “hop on, hop off” service, these liveaboards are most commonly known as “flexible liveaboards”. Daily transfers to and from the flexible liveaboards are made by speedboat travelling from Taplamu pier in Khao Lak, journey time is 1 hour, 15 minutes each way. Overnight trips usually include 6 dives, speedboats leave Taplamu pier in Khao Lak at 8am on day 1, and return at 4pm on day 2. The trips can last 1,2,3 or more days and include all dive equipment rental, dive leaders, food and drinks, and air conditioned twin/bunk cabins.

flexible liveaboard similan islandsExample of a Similan Islands flexible liveaboard

Learning to dive at the Similan Islands

Whether you are a complete beginner or looking to further you dive education, the Similan Islands are a fantastic location for taking scuba diving courses. The calm waters, spectacular scenery, and 30 meter underwater visibility make the Similan Islands a great choice for learning to dive.

Open Water Courses

Before diving in the sea, open water courses require confined water training which takes place in a swimming pool on the mainland. Khao Lak is the main tourist town close to the Similan Islands and is the most convenient and well set up place to base yourself whilst completing an open water course. After a day at the pool you will head to the Similan Islands to complete 4 open water dives and become a certified open water diver.

open water course similan islandsConfined water training pool in Khao Lak

Advanced Courses and Further Education

Other diving courses such as advanced open water, or specialty courses such as deep diving, nitrox, or underwater photography are best taken whilst on liveaboard trips. Liveaboards are a great way to practice your newly learnt skills straight away, and enhance your diving experience at the Similan Islands.

Professional level courses and internships such as Divemaster and Instructor Development Courses are also popular to take at Khao Lak and the Similan Islands. Most reputable dive schools will even help you to find work after you have completed the course.

Similan Islands Marine Life

Small Marine Life

Most experienced divers will tell you that when they first started diving they were only interested in seeing the larger marine life such as manta rays and sharks. But as time goes by and you have seen most or all of what you desired, you start to become more interested in smaller marine life. Before you know it you are completely addicted, and become obsessed with finding tiny little creatures, some of which are only just visible with the naked eye.

Seahorse’s are notoriously difficult to spot, this one at Richelieu Rock during the 2016/17 dive season

The Similan Islands dive sites are home to a vast array of nudibranchs, flatworms, pipefish, frogfish, seahorses, shrimps, crabs and much more. Whilst it is difficult to single out dive sites to see various species, there are a few sites where you can find the same species or resident fish dive after dive. For example at Anita’s Reef you are pretty much guaranteed to see carpets of garden eels along the sand bottom and at West of Eden there is a resident spearing mantis shrimp who has lived in the same hole for 5+ years.

Nightdives are great for spotting smaller marine life, the dive sites most visited by liveaboards are honeymoon bay (island 4), Hideaway Bay (island 5/6) Donald Duck Bay (island 8), and Namchai Bay (island 9). Expect to see lots of nudibranchs, crabs, and shrimps, along with larger neighbours such as moray eels and lobsters.

Anemone Crab spotted at Turtle Rock, Similan Island No.8

Large Marine Life

Larger marine life regularly seen at the Similan Islands include whale sharks, blacktip and whitetip reef sharks, leopard sharks, manta rays, eagle rays, marble rays, great barracuda, and napoleon wrasse.

Huge schools of Barracuda can often be spotted at certain dive sites such as Tachai Pinnacle (Koh Tachai), Three Tree’s (island 9), or North Point (island 9).

Whalesharks are getting harder to find but the well known hotspots are Tachai Pinnacle (Koh Tacahi), Koh Bon, Richelieu Rock (Surin National Park), and Boonsung Wreck (close to mainland in Khao Lak). Usually they swim close to the surface and are subsequently seen by a few lucky divers.

Koh BonWhaleshark spotted at Koh Bon, slightly to the north of the Similan Islands

Leopard sharks can often be seen resting on sand bottoms at depths around 25 – 30 metres. They can be seen all around the Similan’s but most frequently at Breakfast Bend (island 9), Anita’s Reef (island 5/6), and Koh Bon.

This video was shot by our friends at Scuba Bangkok when we joined them on a dive trip at the Similan Islands in January 2016. This magnificent pair of Leopard Sharks were spotted at Breakfast Bend, island No.9

Manta Rays are regularly seen at Koh Bon, Koh Bon is the best place to spot manta rays in Thailand. The islands submerged north and west ridges are the best places to see them, sometimes it is possible to see several magnificent manta rays on a single dive. Manta’s are also regularly seen at Tachai Pinnacle, but can be seen anywhere around the Similan Islands if you are lucky. Manta Rays are mostly seen from January to April.

Manta Ray Koh BonOceanic Manta Ray at Koh Bon

Blacktip and whitetip reef sharks are often seen around the deeper dive sites or rocky points such as Elephant Head Rock, Deep Six, Christmas Point, and Koh Bon.

Common Marine Life

Aside from the very small and very large, there is a vast array of other marine life which are common sights whilst diving at the Similan Islands. Just a few examples of these are: trumpetfish, butterfly fish, angelfish, batfish, clownfish, filefish, oriental sweetlips, triggerfish, giant pufferfish, cuttlefish, octopus, moray eels, hawksbill turtles, banded sea snakes, humphead parrotfish, and many more!

MV Aquatic LiveaboardHawksbill Turtle

Need more information on diving the Similan Islands?

Contact Us for honest independent advice on liveaboard trips, learning to dive, and Similan Islands day trips. We have our own team of dive instructors based at the islands throughout the dive season. About Us.

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Thailand travel expert and scuba diving Instructor for Thailand Adventure Guide.

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