Richelieu Rock, Koh Tachai and Koh Bon – An Unforgettable Thailand Liveaboard Adventure
Our destination for the first day? The famed Richelieu Rock, a gem rising from the Andaman Sea and renowned as one of the world’s great dive sites. And it certainly delivered! As we approached the iconic pinnacle, excitement rippled through the group as everyone prepared to discover what was waiting beneath the surface.
Richelieu Rock Was on Fire!
Richelieu Rock was absolutely on fire this week. From the moment we descended, it was obvious that this submerged, horseshoe-shaped rock was absolutely teeming with marine life.
Schools of Longnosed Emperor, Bluefin Trevally, Bigeye Trevally and Rainbow Runner moved gracefully around the pinnacle, hunting amongst the clouds of Glassfish in a mesmerising display of natural activity. On the north side, huge schools of Chevron Barracuda and Batfish added even more drama to the scene.
But the big fish were only part of the story. Macro enthusiasts were not disappointed either, as Richelieu Rock presented a treasure trove of smaller discoveries. Harlequin Shrimp, Ghost Pipefish and Anemonefish delighted sharp eyes and camera lenses.
Then came one of those encounters that can make an entire dive: a tiny baby seahorse nestled within a sea fan. They are already masters of camouflage when fully grown, but finding one at such a young age was a real challenge. You really have to know where to look!
In fact, tiger-tail seahorses are remarkably small at birth, measuring only around 1.5 centimetres (0.6 inches). Despite their miniature size, they already possess the characteristic features of the adults, including their distinctive markings and prehensile tail. You can learn more about these fascinating animals in our guide to the tiger-tail seahorse.
Koh Tachai – A Botanical Wonderland Beneath the Waves
The following day found us at Koh Tachai, eagerly exploring its underwater pinnacle. Diving here felt almost like strolling through a botanical wonderland, with vibrant hard corals and giant gorgonian sea fans providing the backdrop for an extraordinary variety of marine life.
Groupers of all shapes and colours shared the reef with colourful Surgeonfish, Parrotfish and Butterflyfish. Every corner seemed to reveal something new, whether tucked into the reef or cruising through the open water.
Outside the reef, a massive school of Barracuda provided another spectacular encounter. We also discovered lobster nests, adding yet another layer of excitement to our dives at this impressive Andaman Sea dive site.
Blackwater Diving in the Andaman Sea
But our adventures did not end after our exhilarating reef dives. Some of us decided to embark on a unique and mysterious experience that was still relatively new to many of the group: a Blackwater dive.
We steered the boat westward until we had around 100 metres of water beneath us, then prepared ourselves for extraordinary underwater encounters. As we descended into the dark offshore waters of the Indian Ocean, we entered a completely different world.
Squids, tunicates and an array of juvenile fish appeared out of the darkness. Pufferfish, Goatfish, Flounders and Trevallies drifted through the water column, their tiny bodies and shimmering colours illuminated by our lights and strobes. Every few seconds brought another surprise, keeping cameras firing in the darkness.
Blackwater diving is one of those experiences that can be difficult to explain until you have experienced it yourself. Away from the familiar scenery of a coral reef, the darkness reveals a constantly changing procession of pelagic life, offering a glimpse into one of the ocean’s lesser-known worlds.
Koh Bon – A Spectacular Finale
As our expedition drew to a close, we ventured to Koh Bon for our final dives. What awaited us was nothing short of breathtaking.
Descending to around 30 metres, we found ourselves in the middle of a mesmerising scene: a colossal Marble Ray surrounded by a swirling vortex of Bigeye Trevally, while a Leopard Shark gracefully glided through the background. It was one of those pure moments of underwater awe that reminds us exactly why we pursue the depths — to witness nature at its most spectacular.
Throughout our dives at Koh Bon, we also encountered sharks that we could not identify with certainty, alongside the ever-present Barracuda, Batfish and Trevally. Banded Sea Snakes moving across the reef added yet another fascinating encounter to a trip already packed with marine-life highlights.
From tiny seahorses at Richelieu Rock to pelagic encounters at Koh Bon, the variety experienced during this expedition was a perfect reminder of just how much the Andaman Sea can offer on a liveaboard itinerary.
Celebrating New Diving Achievements
Special congratulations are in order to Joom and Caroline for completing their Advanced Diver course, and to Antoine for achieving his Nitrox certification. Their dedication and enthusiasm for diving were truly commendable, and it was fantastic to see them adding new skills and experience to their diving journeys.
Farewell to the Surin and Similan Islands
As we bid farewell to the Surin and Similan national parks, we extended our heartfelt thanks to our fellow adventurers whose camaraderie and enthusiasm made this journey such an unforgettable odyssey.
From the extraordinary marine life of Richelieu Rock to the colourful reefs of Koh Tachai, the strange and wonderful world of Blackwater diving and the spectacular final encounters at Koh Bon, this expedition delivered a little bit of everything that makes diving in Thailand’s Andaman Sea so special.
Until our next underwater escapade, may the ocean continue to beckon, promising endless wonders for those willing to explore its depths.
Discover More
Planning your next Andaman Sea diving adventure? Explore more about diving at Richelieu Rock, discover the reefs of Koh Tachai and Koh Bon, or explore the wider Similan Islands and Thailand’s incredible marine life.
