Richelieu Rock is a dive site in Thailand in the Andaman Sea about 45 kilometres from the mainland. It is part of the Mu Ko Surin National Park although being about 18 km east of Ko Surin Tai. There are no islands in the immediate vicinity of the reef.
The limestone pinnacle rises from the sea floor of about 30 to 35 m above the surface at low tide. The horseshoe-shaped reef is known for its purple corals as well as diverse marine life ranging from small fish and harlequin shrimp to large pelagics like whale shark and manta ray.
Wikipedia https://en.wikipedia.org/wiki/Richelieu_Rock
Official Website http://www.richelieu-rock.com/
Coordinates 9°21'48.128" N 98°1'15.676" E