Diving at Shark Fin Reef - Similan Islands

One of the larger dive sites at the Similan Islands in Thailand is a place called Shark Fin Reef. Its name derives from the granite boulders which break the surface at low tide and have the appearance of the dorsal fins of three huge sharks. It’s located on the east side of island 3 at the Similans, in the south of the chain. Depths, visibility, coral health and marine life are all excellent, even after the devastating tsunami in December 2004.

Due to its size, Shark Fin Reef can actually be dived twice in a morning or an afternoon. It’s about one kilometer long and lies from north-west to south-east.
Just south of Shark Fin Reef is Boulder City. Although it is not commonly done, it’s possible to fin across from one to the other during a dive. However, currents at the Similans are unpredictable and can be strong. Shark Fin Reef is no exception. Also, water conditions at the surface can be choppy from time to time, but this does not affect the diving once submerged.

Under the water there are dozens of huge granite boulders which make the dive site what it is. Gorgonian sea fans and corals have attached themselves to filter feed, and lots of colourful and interesting marine creatures have made it their home. The two sides of Shark Fin Reef are distinctly different, with the north-east sloping more gently to open, but shallower, water and the south-west side – facing Island 3 – being deeper. This creates a canyon affect, which although strengthening currents, is an extremely fertile area with lots of life.

Expect to see macro invertebrates, regular reef fish and even some pelagic species. Of the larger fish, rays, sharks, Napoleon Wrasse and barracuda are relatively common.

There is something to see within just five metres of the surface and right down to a depth of 40 or more in some parts of the canyon side on the south-west. As already mentioned, visibility is nearly always excellent, mainly because the side closest to the island has the channel running through it and the shallower side is out to 65 miles of open Andaman Sea. The aforementioned currents usually run north-south or vice versa, but one mustn’t depend on this 100%. Going deeper, and away from the tips of the Shark Fin boulders will offer a diver more shelter from such currents.

Due to its location, it is usually dived on the first or last day of any liveaboard trip. However, being susceptible to currents, it is not ideal for a ‘test’ dive on any group’s first day.