The nine Similan Islands are located 100km North West of the popular holiday island of Phuket in Thailand. The word Similan is a variant of the Malaysian word ‘Sembelan’ meaning nine.
All scuba diving, snorkeling and underwater photography activity happens around islands 4-9 which covers 15 popular dive spots.
Island No. 1 is a turtle sanctuary and visits are prohibited by the National park. Islands No. 2 and 3 are also closed to allow the reefs to regenerate.
Donald Duck Bay viewpoint on island No.8
(Photo Spencer Finn)
The nine Similan Islands are located 100km North West of the popular holiday island of Phuket in Thailand. The word Similan is a variant of the Malaysian word ‘Sembelan’ meaning nine.
All diving activity happens around islands 4-9 which covers 15 popular dive spots.
Island No. 1 is a turtle sanctuary and visits are prohibited by the National park. Islands No. 2 and 3 are also closed to allow the reefs to regenerate.
Geography
The islands are a mixture of granite cliffs, boulders and white sandy beaches. Underwater offers a very similar topography. On the east side of the islands there are vibrant corals reefs that gently slope down to a sandy bottom.
On the west side, a very different experience, with giant granite boulders forming dramatic rock formations, with walls, swimthroughs and overhangs.
Climate
The Similan national park is open from the middle of Oct through to the middle of April during the dry season. During the months Oct – April the Andaman Sea is the calmest with a gentle wind coming from the east.
After April, the southwest monsoon can bring strong winds, and the waves may reach 2-3m, so the islands and National park offices are closed until the middle of October.
The weather may also be a little unpredictable during the beginning/end of the dry season, so be sure to check the weather reports.
How to get there
The most popular method of visiting and diving the Similian Islands is by a liveaboard departing from either Phuket, or Tap-Lamu, which is close to Khao Lak.
Most trips are anywhere from 3-5 days and many also include the islands of Koh, Bon, Koh Tachai and the famous Richelieu rock north of the Similan’s .
East of Eden
Located on the east side of island No.7 (Koh Pa yu) is one of the most colourful dives in the island chain with visibility up to 30m. The reef starts at 5m close in to the island, and slopes gently away to the sandy bottom around 35m.
The reef is covered with a multitude of different hard corals, soft corals, sponges, scattered throughout with gorgonian sea fans. The usual fish ,such as snappers, sweetlips, blue fin trevally, dogtooth tuna, moray eels, groupers, turtles abound on the reef.
There are also stacks of small critters, such as Nudibranchs, Ornate ghost pipefish, frogfish and a variety of shrimps to search out.
Coral Bommie East of Eden
(Photo Spencer Finn)
The highlight of the dive is the large coral bommie at the south end of the reef. The top of the bommie starts at 12m and descends down to 20m on the east side.
The huge number of fish and the clear blue water coupled with colourful corals makes for some great wide angle reef shots.
The bluestreak/bi-colour cleaner wrasse here are very efficient; even divers get a good clean, so do not be surprised if you find one cleaning your mask, or feel one cleaning your ears.
The shallow area (5-15m) makes an ideal location for the last dive of the day, or a night dive. Keep a look out for rock lobsters, decorator crabs, sponge crabs and shrimps.
Deep Six
On the north end of island No. 7 there are a collection of boulders with soft coral's and sea fans that extends out from the tip and submerges to 40m.
There are a number of large boulders that have come to rest on one large boulder in the middle to form 3 swimthroughs 12-21m. This is a great opportunity to take your time through the swimthroughs, as there are stingrays, oriental sweetlips, sweepers and snappers to be seen hiding in the shadows.
Away from the boulders (26-35m) be on the look out for White tip reef sharks, Schooling Trevally, fusiliers, snapper and barracuda.
Check the reef for frogfish, ornate ghost pipefish and Ribbon eel’s. Take a good look between the rocks and channels and make sure you do not forget your torch.
The visibility can vary from 15-25m during the season and the area is occasionally frequented by whale sharks and manta rays, so always keep one eye in the blue, especially, during safety stops.
Blue Ribbon Eel
(Photo Spencer Finn)
Due to the formation of the rocks, the current can be strong here. The flow may come from any direction and change many times during a dive. It is also very easy to go deep and this must be avoided, as the swim back can be difficult, especially when coming along in the shallows against the current.
At the shallower part (10-15m) the hard coral gardens provide a chance to see green, or hawksbill turtles, octopus, red fire gobies, nudibranchs, damselfish, Anthias Basslets and clownfish.
Elephant Head Rock
Located just over 1km south of island No.8 (Koh Similan) Elephant Head rock is made up of 3 pinnacles surrounded on the east side by a number of large boulders, which slope down to 35m.
Like Deep six, these boulders have formed a number of swimthroughs on the east side and a channel on the south east side.
Soft coral's hang in the caves and the boulders are home to numerous sea fans. Keep a watch out for Oriental and Andaman sweetlips patrolling the caves and swimthroughs. The rocks and boulders are habitats to Blennies, Wrasse and pairs of red fire gobies.
Oriental Sweetlips
(Photo Spencer Finn)
By heading away from the boulders to the east, or north, white tip reef sharks can be found patrolling the sandy bottom at around 35-40m.
Strong current can swirl around this open site. Especially the full/new moon phases (spring tides) and the surge may also be very strong. So caution is urged when entering the swimthroughs, or getting too shallow and close to the rocks.
There is no mooring line here so you must make a free descent/ascent, making sure that you swim away and well clear of the rocks for your boat pickup.
North point
North Point is a collection of submerged boulders and rocks lying on the north east of island No.9 (Koh Ba Ngu). This site provides both a deep area (35m+) off to the north of the mooring line (which is at 20m) and a nice shallow reef area 10-15m deep running east to west, along the island.
The rock formation creates a nice swimthrough at 24m and a long channel at 15m.
Around the base of the larger boulders (dropping off to 30m+) there are Kuhl’s stingrays and sometimes a blotched fantailray, or Jenkin's stingrays.
Out in the blue are Barracuda, Tuna, Giant trevally and the occasional Napoleon wrasse.
This deep sandy bottom is habitat for resting leopard/Zebra sharks and white tip reef sharks. Pairs of red and purple fire gobies also live around the base of the boulders and fish - spearing mantis shrimps hidden in their burrows await the unwary.
Green Turtle
(Photo Spencer Finn)
The shallow coral reef garden is covered with many different types of stony corals. Octopus also are regularly seen along this reef system, as well as colourful Nudibranchs, red fire gobies and snappers.
Schooling Blue fin Trevally and Small Toothed Emperor’s hunt side by side along the coral heads. Watch out for the Small - toothed Emperor's dramatic colour change as it goes into a feeding frenzy.
Pairs of Dwarf pipehorses can be found at the base of the boulders forming the channel at around 15m.
There may be strong current present, so it is advised to jump in and descend along the mooring line. If you make a free descent it is possible the current will push you away and you will miss the reef.
Once you are down on the bottom around the boulders you are able to follow the contours and remain out of the current. As the boulders and especially the channel are located to the south, it is possible to gain shelter along the island and hang around the shallow reef to end the dive. In this area, divers have the best chances to encounter a number of turtles and Leopard/Zebra sharks.
Breakfast Bend
This sloping hard coral reef system runs along the east side of island No.9, north to south and drops gently from 5-30m. In the shallows are hard coral clusters with sandy patches. Most of the big stony coral gardens flourish in around 10 to 20m covered with Damselfish and Anthias basslets.
Beyond 25m there are sandy areas with colonies of spotted garden eel’s, Kuhl’s stingrays and the occasional leopard/zebra sharks. There is also a resident Napoleon wrasse that is regularly seen patrolling up and down the reef.
The 20m visibility here makes an ideal location for novice divers and students. The shallow water (around 5m) is great for courses, and a great place for snorkeling between dives. The current is mild and its an easy drift along the reef. either north to south, or vice versa, depending on the current. A nice drift dive along the slope at 15m is ideal for wrapping up the 3rd dive of the day.
Nudibranch Halgerda iota
(Photo Spencer Finn)
Snapper Alley
Another dive site on Island No.9 is Snapper Alley, located on the south east corner. This sloping hard coral reef system is a continuation of Breakfast Bend. The visibility here ranges from 20-30m and the dive starts at a depth of 5-10m near the island to a sandy bottom at 30m.
There is a large variety of stony coral's, maize, staghorn, brain, pore, with patches of soft corals and sea fans. The most interesting aspect of this site is the protruding rock formation to the west. Underwater it has a wall scattered with soft coral and sea fans.
Either side of the Pinnacle you will find two swimthroughs, one at about 8m and the other at 18m.
The current here is normally mild, running in an east to west direction and is a good place for novice divers. There are plenty of small marine creatures at this site, so go slow and look under the coral and in between the rocks for nudibranchs, scorpion fish, lionfish and banded pipefish.
Koh Bon
A small island located 16 miles north east of the Similan islands. There are two dive spots here, Koh Bon West Ridge and Koh Bon Pinnacle.
The ridge slopes down to 35 with a wall on the south side and a shallow hard coral garden from 20-10m on the north east.
It is a popular Manta Ray cleaning station from around Jan-May each year. These gentle giant's patrol these waters in search of a mate, they display beautiful acrobatic displays and at times jump clean out of the water. Some of my best Manta ray dives have been here and if you keep calm and don’t chase them, they will come closer, circle and dance around you for an entire dive.
Giant Manta Ray
(Photo Spencer Finn)
When not looking for manta's you will find lots of other things to keep you interested, such as schools of giant sweetlips, snappers, tuna and blue fin trevally. Keep a look out for ornate ghost pipefish, nudibranchs, devil scorpion fish and longnose hawkfish perched in the orange sea fans.
This small pinnacle is located some 200m to the west of the ridge. The top starts at 18m so it is best marked with a shot line and slopes down quickly to 40m+. There can be strong current here so it is best dived at slack tide.
This is also a common spot to find Manta rays and the occasional whale shark circling the pinnacle and moving between it and the ridge.
There is an overhang on the east side at 40m and there will often be Leopard or Nurse Sharks snoozing there.
There are resident schools of blue fin trevally, barracuda and tuna. Keep an eye out for large blotched fantail rays,or Jenkin's stingrays in the sand.
When conditions are good enough it is possible to swim up shallow to around 16m and fin across the channel 200m, or so, to the ridge.
When the visibility is good you can sometimes see reef sharks lurking in the depths around 40m.
Koh Tachai
This island is located 16 miles north of Koh Bon and is home to the one of the Similan national park stations. It boasts 2 dive sites, Tachai pinnacle and Tachai reef on the south east part of the island.
The pinnacle consists of two submerged rock formations, the southern most being the larger of the two. It is flat plateau at 14-16m surrounded by larger number of boulders descending down to 35+m.
The top of the plateau is covered with small soft and hard coral and is often referred to as the Bonsai garden. Look under the coral here for the resident stonefish, ornate ghost pipefish, nudibranchs and frogfish.
Above the reef the water swirls with schools of fusiliers, Trevally, Barracuda, batfish, Tuna, and down deeper around 30m there are sandy patches where Kuhl's stingrays and Leopard sharks hang out.
Leopard/Zebra shark
(Photo Spencer Finn)
During the right months of the year this area is favoured by Manta's. They often stay for weeks, or even months and move between here and Koh Bon while mating courtships takes place.
If you are lucky enough, Whale sharks frequent this spot also as they travel between islands.
The shallow Tachai reef on the east of the island is great for a sunset/night dive as the hard coral garden gently slopes from 5-25m. Go slow on your night dive and look for lots of small shrimp like colourful marble shrimp (Saron sp.), or the Splendid Reef Crab (Etisus splendidus) with its big black claws.
Richelieu Rock
Without a doubt the most famous dive site in Thailand and known throughout the world as a place where whale sharks regularly make an appearance during the months from December on, with the peak around March/April.
About 24miles north east of Koh Tachai, Richelieu Rock is a small pinnacle only rising 1m out of the water at low tide. Underwater, the pinnacle forms a horseshoe shape from the surface to 30m on the southern and northern points.
Whale shark
(photo Spencer Finn)
On the south is a sandy bay with a few scattered rocks, while on the outer edges of the pinnacle you will find clusters of rocks around 25-30m.
The soft corals on this dive site are amazing and spreading across the entire reef with all the colours of the rainbow. Sea fans grow out from the rocks and the cracks that house all manner of macro critters, including Durban dancing shrimp, banded boxer shrimp, mantis shrimp, flatworms, wentletraps, magnificent partner shrimp, Schultz pipefish and cleaner pipefish
Harlequin shrimp
(Photo Spencer Finn)
This site never ceases to provide me with great dives and has something for everyone. There large schools of Barracuda, Trevally, five lined snappers, Fusiliers and Brown marbled groupers.
But those in the 'know' come here to see some special things that are rare or difficult to find. Critters such as Tigertail seahorses, ornate ghost pipefish, Frogfish, Harlequin shrimp, nudibranchs, Spindle and Tiger egg cowries.
One species not so hard to find are the Whale Sharks that turn up every every year and make regular appearances from Jan-April.
Ornate ghost pipefish
(Photo Spencer Finn)
( Copyright Spencer Finn)
Neville Coleman's diving expeditions, fauna surveys, photographic fauna surveys and marine life identification courses include every major group of marine life.
Neville Coleman's expertise in marine life identification extends to the identification of Algae, Sea Grass, Forams, Sponges, Stony Corals, Soft Corals, Sea Anemones, Sea Jellies, Zoanthids, Corallimorphs, Black Corals, Flatworms, Segmented Worms, Crustaceans, Barnacles, Shrimps, Rock Lobsters, Hermit Crabs, Squat Lobsters, Molluscs, Chitons, Univalves, Bivalves, Cephalopods, Octopus, Cuttlefish, Squid, Opisthobranchs, Nudibranchs, Sea Slugs, Bryozoans, Sea Mosses, Echinoderms, Sea Stars, Feather Stars, Brittle Stars, Sea Urchins, Sea Cucumbers, Ascidians/Sea Squirts, Marine Fish, Sharks, Marine Reptiles, and Marine Mammals, all found in the waters around the Similan Islands and Thailand.