Richelieu Rock

Richelieu is a single rock with no land to return to, so a day here means diving the same feature repeatedly rather than moving between sites. Liveaboards on the northern Andaman route commonly moor up and run three or four dives on it in a day, and it reads differently on each one depending on which way the current is running and how much light reaches the coral. Speedboats from the Khao Lak coast can also get there, but the open-water run each way is long and leaves room for far fewer dives.

Standing alone in open water changes how the site is briefed. Current can reverse between dives, so the briefing is usually about which way to leave the mooring line and where to tuck in if it picks up, rather than a fixed route around the rock. Most of the dive is spent working the flanks somewhere between about ten and twenty-five metres before finishing shallow on top. With nothing else nearby, several boats can be working the same small feature at once, so groups go up the line where they can and on an SMB where they cannot.

Two very different dives compete on the same rock. Wide-angle divers hold off the flanks watching open water and shooting the coral against blue; macro divers spend the whole dive on a few square metres, working through soft coral and crevices for frogfish, nudibranchs and cuttlefish. The two rarely mix well in one group, and guides often split people by what they are carrying. Artificial light matters for both, because below about fifteen metres the soft coral reads grey without it.

It is a site for divers comfortable descending a line in open water, holding position in current and ascending without a reference. Newer divers manage it in benign conditions but tend to get the least out of it, since the rewards come from staying still and looking closely rather than covering ground. Traffic overhead is worth taking seriously: stay with the group and surface with an SMB up. Anyone booking specifically for whale sharks should plan several dives on the rock and treat a sighting as seasonal luck rather than an itinerary item.