The dive site Richelieu Rock in Thailand

Richelieu Rock is a very famous dive site which is also situated within the area of the Mu Koh Surin National Marine Park. This dive site is the deepest site of the area and is located some miles away of the 5 islands.

You can dive with Aladdin Dive Safari at Richelieu Rock during the Surin Dive Safari and the Similan Dive Safari.

https://youtu.be/YDJ5wG02Mp4

About Richelieu Rock at the Surin Islands National Marine park in Thailand

Richelieu Rock (called Hin Plo Naam in Thai) is a dive site in Thailand in the Andaman Sea about 200 km northwest of Phuket. It is part of the Mu Koh Surin Marine Park although being about 18 km east of Surin Island.

The horseshoe-shaped reef discovered by Jacques-Yves Cousteau[1] 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, manta ray, barracuda, and grouper.
source: https://en.wikipedia.org/wiki/Richelieu_Rock