Sharkfin Reef

Humphead-or-Napoleon-Wrasse-Cheilinus-undulatus-at-Sharkfin-Reef-Koh-Similan-Thailand-Henry-and-TersiaHumphead or Napoleon Wrasse (Cheilinus undulatus)
Photo by Henry and Tersia
Sharkfin Reef is one of the most southerly of the nearly two dozen Similan Island diving sites. Islands 1, 2 & 3 are closed to the public for turtle protection programmes and ownership by the Thai royal family. This dive site is located out to the east of Island 3 (Koh Payan). It is the largest of all the Similans dive sites, stretching out over one kilometre from its northwest to southeast ends. Its name derives from three boulders which break the surface at most tides, and apparently resemble the fins of sharks.

  • 40 metres on its southern side
  • Often dived twice on the same day
  • Not for inexperienced divers
  • Several interesting swimthroughs

This dive site is among the most exciting of those in the Similan Islands. It offers lots of healthy life, excellent visibility and plenty of space. There are swimthroughs (one of which allows divers to go from one side of the boulders to the other), canyons and options to choose from once under the waves.

It is often the one of the final dives of a Similan Island liveaboard trip, so divers need to be careful about how deep they intend to dive to. The huge granite boulders come right up to the surface, allowing divers to see some kind of marine life throughout the whole of their dive. Although uncommon, sightings of large pelagic filter feeders, such as Whale Sharks (Rhincodon typus) and Manta Rays (Manta alfredi), are reported, especially at the end of the diving season in April and early May. With such good visibility, it is always worthwhile keeping an eye out into the blue, and paying attention to other divers who may have spotted something interesting.

Lionfish-Pterois-at-Sharkfin-Reef-Koh-Similan-Thailand-Ron-CaswellLionfish (Pterois) Photo by Ron CaswellEven if there is a medium to strong current at Sharkfin Reef, this is not necessarily a problem. The currents will go along the dive site, which is incredibly long, so divers can enjoy a drift dive, with occasional breaks when finding shelter in canyons and swimthroughs. One canyon is especially long and large, and an excellent place to look for resting sharks and rays. As mentioned before, it is quite common to dive this site twice; once on the deeper south side, then again on the north. The southern side of Sharkfin Reef has a steep wall which descends down to 40 metres. On its northern side, the reef slopes away quite gently as it descends down to the bottom. Some species which are rarely seen at other Similan dive sites are more common here. For example the Humphead/Napoleon Wrasse (Cheilinus undulatus) and Humphead Parrotfish (Bolbometopon muricatum), both of which are large bony fish which normally swim slowly and alone.

Like much of the diving at The Similan Islands, coral bommies and large sea fans are to be found all over. They feed on micro-organisms in the passing currents and are rarely disturbed by human activity, enabling them to grow large and healthy and live long. However, now that the largest swimthrough has been discovered here, divers need to be careful while passing through, in order not to damage the hard corals and fans which make the most of the concentrated channel of water here.

Diving at Sharkfin Reef is both interesting and exciting. Experienced divers can use it as a playground, with the canyons, swimthroughs and occasional currents as their toys. Getting there must be done by liveaboard dive boat or a day trip on a speedboat, although these tend to spend more time at the central and northern Similan diving areas. We have offers for all kinds of trips to the Similan Islands, so just click here to find the perfect diving package to suit your needs, schedule and budget.


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