Diving Richelieu Rock: Thailand's Best Dive Site

Ask Thai dive guides to name the country’s best dive site and most will say Richelieu Rock. This lone limestone pinnacle in the remote northern Andaman Sea, near the Surin Islands, manages to be several great dives at once — a big-animal site where whale sharks and mantas appear, a soft-coral spectacle draped in vivid purple, and a macro hunting ground rich in tiny, rare critters. It is the crowning site of a northern Andaman liveaboard, and for many divers the single best dive of the trip.

This guide covers what makes Richelieu Rock special, when to go, how to dive it, and what you will see. For the wider country picture, see the Thailand diving guide.

What makes it special

Richelieu Rock is a horseshoe-shaped pinnacle that climbs from deep water almost to the surface, and its appeal is breadth. The rock is famous for the purple and pink soft coral that covers it, glowing when a light hits it. Around and above it gather dense schools of fusiliers, snapper, and barracuda. And it is Thailand’s most dependable site for the big animals — whale sharks and manta rays — that pass through in season. Layered underneath all that is some of the best macro in the Andaman. Circling the pinnacle, you can go from watching a whale shark to photographing a seahorse within the same dive.

When to dive it

Richelieu Rock is diveable during the Andaman open season, roughly mid-October to mid-May, but the site is at its best from February to April. That later window brings the calmest, clearest water and the strongest chance of whale sharks and mantas, which appear mainly in those months. Outside the open season the northern Andaman is closed to diving entirely, so timing is not flexible.

How you dive it

Richelieu Rock sits far out in the northern Andaman, beyond comfortable day-trip range for most operators, so it is dived by liveaboard out of Khao Lak — typically as the highlight of a Similan Islands and Surin itinerary. A few day trips from the far north reach it in the calmest conditions, but the liveaboard is the standard and most reliable way to dive it, usually with several dives on the pinnacle to work its different depths and moods.

Who it suits

The pinnacle is exposed and can carry current, so it rewards divers with some experience and solid buoyancy — both to hold position on the wall and to move safely around the rock. Newer divers dive it successfully with good guiding, but a few logged dives and comfort in current will get far more out of it. It is a site worth being ready for.

Shooting Richelieu Rock

From whale sharks to seahorses on a single dive, Richelieu Rock spans wide angle and macro, and as everywhere water strips warm color with depth and distance, so images need correcting afterward. It is worth understanding why underwater photos look blue and how to restore underwater photos. Our camera guides cover the gear, and the before-and-after gallery shows the results.

Plan your trip

For how Richelieu Rock fits the wider region, see the Thailand diving guide and the month-by-month Southeast Asia diving calendar. The full dive destinations hub collects every guide on the site.