Welcome to Richelieu Rock
You are likely to do more than one dive here, so you will probably swim several different routes around Richelieu Rock. The route can depend on which direction the current is traveling, what special marine life is currently known on the site and also you diving experience and air consumption. The route we will focus on here is assuming no strong currents. It is fairly common to dive around the North side of Richelieu Rock first, as this is the deepest part of the dive site.
Jump in near the only buoy line on the South East. Hold onto the line to make your descent easier and this will bring you down to around 14m. Once you are near the rock, you can let go of the line. Even if there are strong currents, there will always be somewhere on the site that is protected, as the rock rises so close to the surface. If the current allows then swim to the far East and start to head North. The picture below shows the steep wall on the East side of Richelieu Rock. Notice the soft corals and anemones sitting on top. Try to spend some time on top of Richelieu as the colour is astounding.
For experienced divers using Nitrox, swim out to the deeper pinnacle at the far North East. This smaller pinnacle is between 25m-35m, but the soft coral is even denser and more beautiful than the rest of the dive site. Once you are finished, turn back South West to the main pinnacle. Keep heading West along the North wall.
Look out into the blue for schools of Barracuda, Trevally and Jacks. Closer to the pinnacle are the large schools of Bigeye Snapper which you can swim straight through. Keep your eyes open for all the smaller creatures. There are plenty of Peacock Mantis shrimp, white eyed Moray eels, nudibranchs, tomato clownfish and much more.
Usually there will be one or two Tigertail Seahorses somewhere on the North side. Check with your divemaster for where they have been most recently spotted. The same is true for Ornate Ghost pipefish, pineapple fish and frogfish. If you have a good eye, you might find them for yourself.
Follow the North wall all the way round to the West side. If you keep swimming around you will eventually reach the shallower bay in the South. The shallow bay is a good place to look for Harlequin shrimp. Harlequin shrimp are very small so it is usually easier to look for their food. They cut off seastar legs and bring them back to their hiding place. If you see a single seastar leg (red or blue) on the sea floor, there is a good chance that a Harlequin shrimp is close by.
You can keep shallowing up towards the end of the dive as there are still things to see in the shallows. Sometimes large lobsters are seen in the cracks on top of Richelieu rock. Cuttlefish are often seen mating or laying their eggs in a small hole somewhere. Big reef octopus can also be seen sitting on top of the pinnacles.
The variety of life here is unparalleled in Thailand and there is always a good chance that you will find something you have never seen before, no matter how experienced you are. Lastly, remember to listen for other divers banging on their tank. If you hear frantic tank banging, there is a good chance that a Whale shark has made an appearance somewhere around Richelieu Rock.