- Location: Surin Islands - 14km (7.5 n.miles) East of Mu Koh Surin
- Site Depth: 0 - 45 meters
- Site Visibility: 10 - 30 meters
- Currents: Can be strong
- Difficulty Rating: Intermediate
Discovered and named by Jacqus Cousteau this dive sites consists of a horse shoe shaped rock that only breaks the surface at low tide. Here you will find very large schools of big eyed trevallies, chevron barracuda, and snappers. On the reef itself you will see lionfish, scorpion fish and octopus, and look in the small cracks and crevices for numerous types of shrimp. It is even possible to find harlequin shrimps. Do not forget of course the chance for whale and guitar sharks.
Richelieu Rock is considered to be one of the best places on the planet to meet whale sharks. This place has an incredible amount of different coral reefs and formations, that drop away 35 metres straight down from the surface. It is believed that there is more than 300 different species of coral here!