Intermediate Thailand
Richelieu Rock
A solitary pinnacle in the open ocean, purple with anemones and famous for its whale sharks
A single limestone pinnacle in the middle of the Andaman Sea, so isolated that it barely breaks the surface at low tide. You dive it by circling around it, and its fame rests on two things: the purple color covering it and the chance that a whale shark might show up.
In this profile you'll find why an isolated pinnacle concentrates so much life, how you dive by circling a single formation, when the whale shark shows up and how honestly that expectation needs to be handled, and what level the current demands.
It's Thailand's most cited dive and a perfect example of why an isolated underwater mountain works as a biological magnet in the middle of nowhere.
Geography and access
Richelieu Rock is a horseshoe-shaped limestone pinnacle located in open water north of the Similan archipelago, far from any coastline.
Its top barely breaks the surface at low tide, and the rest of the formation descends to about thirty-five meters, surrounded by deep water on every side.
That isolation is exactly what makes it a magnet: it's the only relief for kilometers of open water, so everything that needs structure (from invertebrates to schooling fish and passing pelagics) ends up concentrating there.
The rock is covered in anemones, soft coral, and sponges in purple and pink tones that give it its characteristic look and account for much of the site's photography.
It's only accessible by liveaboard or on very long day trips from the coast, and it's part of most Thai Andaman itineraries. It's dived only during the park's open season.
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