This is in the top three favourite dive sites of nearly every divemaster and dive instructor with experience of diving in Thailand. Here you can expect to see anything from Sea Horses, Ghost Pipefish and Harlequin Shrimps to big fish like Manta Rays, Guitar Sharks and Barracuda. Out in the blue Giant and Blue Fin Trevally hunt, sweeping in making the shoals of Glass fish and Snapper stream over the reef. Beautiful, purple, blue and white soft corals cover the outside of the rocks, with carpets of anenomes are home to Clown Fish. Bright yellow Encrusting Anenomes add spots of colour.
Look out for white eyed Morays hunting in the cracks and crevises, this chap was having a clean up by one of the local crabs!
Richelieu rock is shaped like a horse shoe stretching from the surface down to about 40 meters. Rumour has it that it was discovered by Jacque Cousteau and there are several stories of how Richelieu got its name, some say it is after Cardinal Richelieu with the reds and purple coral. My personal idea is that it is named after a French style of embroidery pattern whereby you embroider around the outside, then cut out the centre. There can sometimes be a current and visibility is rarely better than 25 meters.