Richelieu Rock:One of the most amazing dive sites in Thailand



Richelieu Rock. Many people who know Thai dive sites say that the site is the most famous and popular in Thailand. Nearly ten years past since I first met the site. I’ve visited almost every year. The Rock has been attractive, although its beauty has been continuously changing. 


What is the Richelieu Rock?

It is a solitary rocky reef in the Andaman sea, locates 200 km northeast of Phuket, Thailand. It is part of the Mu Koh Surin marine park, although about 20 km east of Surin Island, between the islands and the Malay peninsula.

You can get there by liveaboard departing from Phuket or Khaolak or participating in a diving day trip from Khaolak. The season when you can dive is from about November to April. There are some diving shops providing access to there in Phuket and Khaolak. The regulation for entering the national park of Similan and Surin has gotten strict since Autumn in 2018. There is a limit to the maximum number of entries, so it is advisable to make a reservation to dive the site in advance.

This Rock is horseshoe-shaped, or you can say it is croissant-shaped. You can see the top of the Rock above the surface in low tide, and the Rock is completely hidden under the sea in high tide. It is a relatively compact size that you can swim around in one dive, but there are many exciting things to see. I recommend you to have two or three dives if you come to the site. You can usually have two dives in a day trip and three dives if you get on a liveaboard.

Let’s move on to the attractive features of the site.

In a word, Filled with fish, and colorful.

The site is full of living creatures ranging from whale sharks to tiny nudibranch. You can see huge schools of giant trevally, big eye trevally, barracudas, fusiliers. There are tremendous numbers of reef fishes. Cuttlefish and lionfish are also club members.

Why are so many creatures gathering packed there? Because there is no island and any reef rock around the site. Planktons in the current concentrate around a reef rock or island. Almost every creature in the sea depends on plankton. Richelieu Rock is not so immense. It means that every animal is pack in one place. The density becomes so high that you can see every interesting thing without swimming a lot. You can’t see far away even when the visibility is excellent because there is still a fish wall.

Colorful and flourish soft coral

Every surface of the Rock is covered with colorful soft corals. They are pink, red, and purple changing upon the condition of light. You can imagine flower gardens on a mountain.

Many kinds of fish are swimming in the soft coral garden. Depending on the season, the garden has many arrow cardinalfish (Rhabdamia gracilis) on its surface. They are reflecting lights in every direction. The flower garden is shining. That is really beautiful scene. There are flying green and blue moon wrasse (Thalassoma lunare) in and above the soft coral garden, adding more colors. You can admire the beauty of colors even with the naked eye, but a torch is advisable to savor it.

The soft coral blooms depending on the current. They sometimes miserably wilt when there is no current. The strength of the current is constantly changing. So, you should try two or three dives there.

Secret yellow soft coral garden

You can enter a yellow soft coral garden, although most of the garden on the Rock is pink, red, and purple. It is near the bottom. I’m not sure why it is yellow only in this area. Anyway, you also enjoy another combination of colors, red, coral hind (Cephalopholis miniata), pink sponge, and arrow cardinal fish again. 

Yellow clouds: bigeye snapper (Lutjanus lutjanus)

Large schools of bigeye snapper are seen at several places of the site. They sometimes surround us like a cloud. The color contrast between soft coral is also astonishing.

You can plunge into the school. The school sometimes scatter but never leave the site. They come back again after a while.

Whale shark

Sorry to tell the truth, not every time. But they appear on the site more than once every season. Every once in a while, there are seasons when whale shark swims around the Rock almost every day. You can see them many times in one dive in that case.

An exceptional feature about whale sharks in Richelieu Rock is that we have a chance to observe them in collaboration with colorful soft corals and schools of big fish.

Again, Richelieu rock is such a solitary rock that stands from the bottom of 30 meters deep to the sea’s surface. Every fish is packed around a small area. The Rock is covered with pink and purple soft coral and green seaweed. Whale shark that comes there swims that colorful and life-rich rock. That means we have a chance to spot them with the colorful and life-rich background. Although a whale shark with a blue background is still satisfying, that is much more photogenic. The scene of a swimming whale shark followed by a big school of trevally is awing.

A school of fish, a school of fish, a school of fish.

I’m always really excited when I see big schools of fish. We can meet schools of blackfin barracuda and big-eye trevally. We also have a chance to see a school of young giant trevally, depending on years. Blackfin barracuda swims in the relatively shallow part. Big eye trevally and giant trevally swim usually in the middle.

It is magnificent to meet huge schools though the scale of a school depends on the season. One of the most exciting scenes of the site is that two schools of other kinds of fishes meet each other or a whale shark swim in the schools. 

Lovely small fishes

Richelieu Rock is not only for wide-angle features, but you can also spot small creatures which are popular among divers.

First of all, Tiger tail seahorse. It is in a yellow and striped pattern, like a tiger from the body to the tail. Their inhabitant is near the bottom. It is essential to request your guide to find them before the first dive. It is difficult to find them by yourself, and you may lose a chance to see them in the second or the third dive because of depth, depending on the diving plan.

Endemic anemone fish is seen here, Tomato anemone fish. Vermilion red body with a single black spot on each side is the special feature. Vibrant color, in my opinion. Young fish has a white line on head, kawaii in my opinion.

There are also harlequin shrimp, relatively large, clear pattern one, ghost pipefish in various colors, Primovula tigris, flashy tiger-colored snail, and tiny but colorful and photogenic gobies. Why don’t you take a photo?

Green pasture and blue sky

The Rock has a pasture on the top. From 5 meters below the surface to the top of the Rock is covered with green algae. Beautiful scene of green color is relatively rare in the tropical sea, although the sea is full of other colors, like red, yellow, pink, purple, and blue. You can request your guide to take time to admire the scene before exit. Please don’t forget if you are interested.

Turtles or giant trevallies are sweeping on the surface of the pasture. In low tide, waves hit the Rock, water splashes and tiny bubbles shine in the sunlight. With scattered colorful small fish, it is like a kaleidoscope.

Sunset: the active moment

There is a chance to dive around sunset if you get there by a liveaboard. Sunset is a miracle time that most kinds of fishes are activated. There is a tremendous amount of fish around the Rock, even in the daytime, and you can imagine what happens at sunset.

My favorite dive shop

Many good shops operate liveaboards and day trips to Richelieu rock, but I like Big Blue Diving. I’ve been on their boat many times. There were very friendly and skilled dive masters on the liveaboard, and I had a great time each trip.

Big Blue Diving Khao lak


  1. That’s some beautiful picture of Richelieu Rock, well done!
    One of my favourite dive site in Thailand.