Boulder City

Similan Islands dive site

Boulder City manta rayLocated 3km off the east coast of Koh Payan (Similan Island number 3), Boulder City forms a chain, with Shark fin reef to the north, of submerged boulder formations. Due to it’s southern location in the Similan Islands group it is often the last dive site dived on a liveaboard trip before the long sail south to Phuket.

Dives at Boulder city can be challenging as the site is exposed and currents can be strong. There are mooring lines on the site and these are often used for descent and safety stops before ascent.

Boulder City is characterized by large granite boulders stacked on top of even bigger granite boulders sitting on the sandy bottom. These boulders provide a stunning underwater seascape and because they are in open sea away from the islands they can attracted bigger fish such as whale sharks and manta rays.

Giant barracuda, dogtooth tuna and mackeral are also common as this dive site has many cleaning stations.

The boulders drop down below 35m and a typical dives involves descending deep and then working your way back up, in and around the rocks, seeking protection from the current where necessary. The boulders are generally smooth with few corals although there are patches of soft coral and crinoid growth.

Seafans and sea whips feed in the currents at the sides of the boulders, sometimes blocking a divers route through a rocky valley. Sea urchins wedge themselves into the cracks. Lionfish and scorpionfish also like the cracks in the rocks as do moray eels. Grouper and parrotfish are always busy. Oriental sweetlips can be seen at home under small table corals.

Leopard sharks and whitetip reef sharks are seen in deeper areas. The eagle eyed diver may also be able to spot purple fire gobies. Longfin batfish will probably keep you company on your safety stop.

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