Diving at Similan Islands

Similan Islands Dive Sites Guide

Koh Similan is by far the most beautiful group of dive sites that we have in Thailand and one of the best areas for diving in the entire world. Many people comment that the most fantastic thing about the Similans is that we have two radically different types of environments all rolled together into one destination. Nowhere else in the world will a diver find such diverse environments in such a small area.

The Similans, located about one hundred kilometers northwest of Phuket, are composed of nine granite islands covered in tropical jungle, washed by a clear blue tropical ocean and blessed with some of the world's finest beaches. Similan comes from Malay fisherman who named it "The Nine Islands" (Sembilan is "nine" in Malay) and now the islands are identified by a name -- in Thai and a number -- for example, Koh Huyong (Island #1), located at the southern end of the chain.

The islands have achieved national park status and thus are fully protected under Thai law. The National Park Authority maintains its presence on two of the islands: Koh Similan (Island #8) the largest, and Koh Miang (Island #4). Recently, the islands have come to the special attention of the Thai Royal Family which further protects them from possible abuse. 

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By drawing an imaginary line from north to south, we divide the area into our two separate types of environments. The east coast, with its powdery beaches, features hard coral gardens which slope dramatically from the surface down to approximately 30-40 metres, where sand takes over as the water depth increases. On this side, the most popular activity is drift diving along healthy coral gardens while watching the reef inhabitants go about their business. In several sites, large coral bommies rise from the bottom and are covered with soft corals, sea fans, and an enormous amount of critters and unusual fish. Here the diving is easy and navigation simple, allowing each buddy pair to explore at his or her own pace.

The west coast, just a short boat ride away, can offer faster paced, more exhilarating diving as currents swirl around the huge granite boulders-some larger than the largest of houses. These smooth, rounded boulders make dramatic formations, holes, and overhangs ("swim-throughs") underwater where divers can enjoy swimming with the current through the openings. The drama of just looking up through the clear water at these huge rocks is satisfaction enough for some divers, as there are very few places like this on earth. Growing on these boulders are some of the most colorful soft corals imaginable, in many places so thick that the rock is no longer visible. In the larger passages or channels between the boulders, the fans grow to a size sometimes three metres across, and are often so tightly bunched together that it makes it impossible to swim through the passages. Most of the dive sites on the west coast are best seen with a guide, since navigation can be tricky.

If you enjoy watching and photographing small fish, the Similans are hard to beat for the sheer numbers and varieties of tropicals. Large fish, however, are a different story and the Similans are not well known for consistent big fish action-stories about which fill all the popular diving magazines. For this kind of diving, you must travel further to the Burma Banks. Luckily, we often do get an occasional whale shark, while large cow tail rays are fairly common. And, of course the most famous aquatic resident of Thailand-the leopard shark-makes his appearance on a regular basis. We'll also see white tip and black tip sharks once in awhile, and a few times over the years we've seen schools of pseudo orcas or false killer whales.

The point is, like all diving areas, enjoy the Similans for what they are famous for; wild, unspoiled beaches, magnificent coral growth, prolific fish life, crystalline blue water and sensational underwater rock formations.

The only accommodation available on the islands is on #4 which has both tent camping and Thai style bungalows. Getting to the Similans to enjoy life on the island however, is not easy; day boats run to the islands irregularly at best. The best way to visit the Similans are, and will continue to be, on a live-aboard boat.

Boats in Thailand vary in style and comfort dramatically. For those less worried about comfort, sleeping in one big cabin or even on deck will save you money. At the other end of the scale, several boats are available with large, private air-conditioned cabins, professional photography services, modern communications, and little extras such as gourmet meals, video, and CD sound systems. These boats also have the stability, the range, and the navigational equipment to explore areas north and west of the Similan Islands such as the Burma Banks and Richelieu Rock.

Trip lengths vary from three to five days; often longer if the boat is including the Similans as just one stop on the itinerary. One day trips are possible at certain times of the year but in general are not recommended as it is impossible to fully appreciate the beauty of the islands without spending a few days diving around them. Trip prices vary dramatically-starting at $400 and peaking at about $3,000-depending on where you go and how comfortable you want to be.

High season in the Similans is from October until May, but diving is possible all year-round. The water tends to be clearest in the summer and in the fall, but then again, the visibility is usually good in the Similans, averaging approximately 18-25 metres and at times exceeding 40 metres! There are well over 20 charted dive sites in the Similan chain, and the following short descriptions of a few of our favorites should give you an idea of what to expect. 

Similan Islands Dive Sites Description

Christmas Point, Island #9, Koh Bangu

One of the most dramatic dives in the Similans, this dive begins with a series of large arches at a depth of about 24 meters. The soft coral growth and sea fans are as large as they are anywhere, and the fish action is fast here. We often encounter small schools of blue fin trevally feeding on schools of fry. End your dive near the island for the best swim-throughs in the Similans and keep your eyes open for surprisingly large jacks that hide in these passageways.

Breakfast Bend, Island #9, Koh Bangru

A typical east coast dive, this is my favorite way to begin a trip. The light is beautiful early in the morning hence its name, and the coral is in great shape. Down deeper in the sand, there has been a large increase of garden eels over the past few years. In the shallows, leopard sharks are often seen resting in the sand. Recently we've spotted a napoleon wrasse, which is a rare fish in the Similans.

Fantasy Reef, Island #8, Koh Similan

One of the most popular dive spots in the Similans, these underwater rock formations cover a huge area. The friendliest fish in the Similans hang out here, including clown trigger fish, normally a difficult fish to approach. Depths range from 15 meters down to past 40 metres, and this is one of the best dives for enjoying the grandness of huge boulders. One of the best dives I've had here was a couple of years ago were we viewed at least 10 cow tail rays over the sand-some animals exceeding 3 metres in overall length-participating in a frantic mating ritual.

Beacon Reef (South), Island #8, Koh Similan

One of my favorite dives, probably because this is where I saw my first whale shark, this reef features a steep drop-off with striking diversity of hard corals from 35 metres of depth almost all the way to the surface. This dive probably has the largest variety of healthy hard corals in the Similans, probably exceeding 300 species. I enjoy poking around the coral heads looking for nudibranchs and the nervous fire fish (Nemateleotris magnifica), one of the most beautiful fish in the tropical sea. One of the ugliest residents of this reef are the big eye fish that slowly cruise the reef flats. These fish have an amazing ability to change from a deep red color to a contrasting vivid silver. It almost appears as if they are changing their color to fit their mood.

Elephant Head, Island #8, Koh Similan

Probably the most famous dive in the group, the site is named after an unusually shaped rock that juts out of the water just southwest of Koh Similan. The three rocks that form Elephant Head also create a natural amphitheater that feels like you are diving in a huge aquarium. Yellow goat fish and snappers always hang around at the deepest level of the bowl, as well as several species of lionfish, coral trout, and the occasional hawks bill or ridleys turtle. The swim throughs at deeper depths are dazzling.

East of Eden, Island #7, Koh Payu

A typical east coast dive, this particular site has one of the most incredible underwater bommies in the Similans. Beginning at about 21 metres and continuing up to about 12 metres, the concentration of marine life is unequaled in the Similans. For a period last summer, we had the opportunity to photograph a cute pink frog fish repeatedly, as he stayed in the same spot on the same reef for over two months. These are rare fish in the Similans anyway, but he was especially fun as he was so regally positioned on top of his throne of coral.


In the End

The Similan Islands are unique for another reason as well. Mooring projects and other environmentally protective measures have been introduced over the past few years and happily, the diving has actually improved. While we hear that other areas of the world deteriorate due to thoughtless management, the diving in the Similans just gets better and better. One thing's for sure, the Similan Islands will give all that you ask of it-and more.
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