Shark Fin Reef at the Similan Islands in Thailand is a formation of granite boulders and hard corals about 1 km southeast of Similan Island No. 3, good for advanced scuba divers.

Shark Fin Reef itself is approx. 1 km long and lies from the northwest to the southeast of the Similan Islands. Normally 3 pinnacles resembling sharkfins can be seen from the surface which give this site it's name.

Most of the dive site is hard coral, soft coral and seafans with a maximum depth for scuba divers of around 35-40 meters.