Discovered by marine explorer, Jacques Cousteau himself, the dive site is part of the Mu Koh Surin marine park not far from the Thai-Burmese oceanic border. This inconspicuous rock, the pinnacle of which is only visible breaking the surface at low tide is situated 18 kms east of the Surin Islands and is often considered a navigational hazard for boats. But underwater, the horseshoe shaped dive site with it’s steep walls, groups of rocks, small caves and south side bay with a slope that gently falls to the deep is thriving with marine life so rich and diverse that several dives here doesn’t do justice to it’s beauty.
The Rock was said to be named by Cousteau, after Cardinal Richelieu of France as he was reminded of the clergyman’s robes when he saw the rich purple soft corals that blanket the rock in abundance. Every square inch of the huge rock that goes down to 35 meters (115 feet) is covered is mostly colorful soft coral, accompanied by huge sea fans, hard corals and sea anemones. The diversity of life at this one dive site is truly incredibly. With the tiny harlequin shrimps, ghost pipefish, tiger-tailed seahorses, peacock mantis shrimp, frogfish and more the scope for spotting macro life is endless especially for underwater macro-photography.
And just when you think, that’s all you would need to be convinced it’s a good dive site, it gets even better. Due to the location of the rock in the middle of open waters, makes it a hotspot for pelagics that swarming the rock constantly. Schools of chevron barracudas, plenty of Bigeye Trevally, Fusiliers and Snappers circle the outcrops of the dive site. On the sandy slopes of the south site you can often spot giant groupers, leopard sharks and the usually elusive guitar shark!
Although, you would have heard that there are many sites in Thailand for diving spotting manta rays and whale sharks, Richelieu Rock is your best bet. The nutrient-rich water with it’s rich plankton blooms attract many fish including the world’s largest fish -the whale shark. In fact it’s rated among the top places in the world to encounter the gentle giants. The best season for this is February to April. Manta Rays too frequent the site.
The best way to dive Richelieu is via liveaboards that leave from Thap Lamu port in Phuket, Thailand and usually do a route that includes the Similan Islands, Koh Bon, Koh Tachai and Richelieu Rock. There are only a few day trips that visit there mostly from Khao Lak, but because of the distance these trips take very long. Currents can make diving this site a little tricky, but with a good dive guide you can he’ll know how to guide you to take shelter by the rocks and plan your dive well so you get to see a variety of what the dive site has to offer. In my opinion, even several dives later you’d have only scratched the surface of this abundant dive site, but one thing’s for sure…you’ll leave saying Richelieu Rocks!