Richelieu Rock is without a doubt Thailand's best dive site ! The site is large, full of marine life and you often need 3 dives to really appreciate it! The reef is superb, especially the soft corals that cover the entire site, many large pelagics are present and we can come across leopard sharks and manta rays. There is above all a whale shark season at Richelieu rock from January to April, so come at the right time! If you are planning a Similan Islands diving cruise, you owe it to yourself to go to Richelieu Rock !!

# Presentation
# Diving with
# Season and conditions
# Origin of the name
# My diving review

plongee requin baleine richelieu rock thailande

The full article on diving in Similan Islands here


Where is Richelieu rock?

  • Richelieu Rock is a dive site that is located At sea east of the Surin Islands in Thailand.
  • It turns out that above the Similan Islands, Koh Bon and Koh Tachai. The site is part of Surin Islands Marine Park since 1988.

carte ou se trouve richelieu rock en thailande

Topography of Richelieu rock

richelieu rock above 2-min

  • The topography of the site looks like a horseshoe shape, with a huge pinnacle principal in the middle scarcely see the summit only at low tide, see photo opposite) surrounded by other smaller pinnacles.
  • They are placed on a sandy area, the maximum depth of which is around 35-40 m.

carte plongee topographie richelieu rock thailande

The story of Richelieu rock


  • It's still our Jean-Jacques Cousteau which has discovered Richelieu rock (as Cozumel or Sipadan for example) !
  • When arriving in the Adaman Sea in Thailand, Commander Cousteau simply asked the fishermen "where are the fish?" "," What are your best fishing spots? », And lo and behold, they took him to Richelieu rock !!
# Presentation # Diving with # Season and conditions # Origin of the name # My diving review


Diving cruise at Richelieu rock

  • Richelieu-rock-corail-moue2-minThe site being in the middle of nowhere and far from the coast, it is very hard to go diving there for the day!
  • To dive Richelieu Rock it will take do a liveaboard diving cruise from Khao Lak by combining it with the Similan, Koh Bon and Koh Tachai islands.
  • More info on dives to Similan Islands in this article.

Whale sharks Richelieu rock


  • Richelieu rock is well known for his whale sharks.
  • Indeed, in season (January to April), it becomes a place of passage for these giants of the seas.
  • Nothing is guaranteed of course, but if you do 3 dives at Richelieu rock during the right period, there is a very good chance that you will see one !!

Manta sharks and rays


  • This is not the spot where you will see reef sharks in all directions, but you can sometimes cross feeding sharks and leopard sharks.
  • Some manta rays sometimes pass by there, especially during the whale shark period (January-April) when the waters are loaded with plankton.

Big Pelagic

plongee Similan 20

  • There is a lot of large pelagic who may catch your attention while diving at Richelieu rock
  • Some big malabar groupers a good meter long (Malabar grouper), barracudas benches, rainbow runners, trevally (bigeye trevally), fusilier, snappers of all kinds ...

Other pelagics

plongee Similan 16

  • We also find all the fish of the sea of Adaman
  • Namely sea turtles, balloon fish, trunk fish, lots of morays (giant, zebra, white-eyed ...) who wander along the rocks in search of a small hole where to put, batfish, clownfish ...

Reproduction of cuttlefish

plongee Similan 11

  • Richelieu Rock is filled with cuttlefish !
  • They reproduce here, each dive is therefore an opportunity to see the males (sometimes 2, 3 or 4) trying to "seduce" the female.
  • A rare event to observe.

Macro Paradise

07 Nudibranch -Magnificent chromodoris 3

  • The site is full of little creatures which will delight photographers!
  • Some seahorses, the ghost fish (ornate ghost pipefish), harlequin shrimps, anemone shrimps, fish pipes, frog fish, porcelain crabs, scorpion fish, mantis shrimp and a very large variety of nudibranchs !

A preserved coral


  • The whole site is very rich in coralhe is covered with splendid soft corals pink / purple), anemones, gorgonians, barrel sponges…
  • A feast for the eyes !



# Presentation # Diving with # Season and conditions # Origin of the name # My diving review


The diving season at Richelieu rock is from October 15 to May 15.

When to dive at Richelieu rock?


  • Whale shark season Similan islands (Richelieu rock) : January to April.
  • We sometimes see manta rays from December to April.

Richelieu rock diving conditions:

  • Visibility Richelieu rock : from 20 to 30 m.
  • Water temperature Richelieu rock : 27 to 30 °.
  • Current Richelieu Rock : it depends on the sites, but not reputed to have strong currents.
# Presentation # Diving with # Season and conditions # Origin of the name # My diving review


The origin of the name Richelieu rock is still debated! There are two versions:

From Cardinal Richelieu


  • Some claim that the name "Richelieu rock" comes from Cardinal Richelieu.
  • One of the hallmarks of Richelieu rock is the amount of coral pouting pink / purple which covers the entire site.
  • Returning from his 1st dive on Richelieu rock, the Captain Cousteau exclaimed that the rock had been covered by the dress of Cardinal Richelieu (see photo) which has the same type of color as the soft corals present (pink / purple).

From Admiral Richelieu

  • The other, more "pragmatic" theory is that the name would come from admiral Richelieu, a Belgian who was the first admiral of the Thai navy.
  • In the 1960s, the government asked him to draw up a map of Thailand's waters, and it was during this campaign that he discovered Richelieu rock and gave it its name.
# Presentation # Diving with # Season and conditions # Origin of the name # My diving review


As much as I can say that Similan Islands diving cruise (including Koh Bon and Koh Tachai) is not worth a cruise to Raja Ampat, at Komodo or to Tubbataha, as much I must admit that I really enjoyed Richelieu rock ! I did 3 dives and my eyes haven't stopped looking all over the place ! There is always something to observe, whether it is a school of jacks hunting, mating cuttlefish, seahorses or ghost fish to look for, a shark feed who passes by or simply admire the beauty of the coral which covers the rocks! Richelieu rock is a must, the most beautiful site in Thailand !!

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