This expedition through the Andaman Sea unfolded as a gradual exploration of both landscapes and marine life, shaped by shifting currents, encounters, and the quiet surprises hidden along the reefs. While we don't have photos for every sightings, we had some really special encounters!!! The highlight was probably a snaggletooth shark and Bowmouth guitarfish two very rare of the many sharks and rays seen this week!!!
From the dramatic limestone formations of the South Andaman to the exposed pinnacles of the North, each dive revealed a new layer of biodiversity. From the sheltered bays of Koh Phi Phi and Koh Lanta to the dynamic sites of the Similan and Surin National Parks, the week developed into a seamless blend of colourful reefs, schooling fish, and intricate macro life.
From the dramatic limestone formations of the South Andaman to the exposed pinnacles of the North, each dive revealed a new layer of biodiversity. From the sheltered bays of Koh Phi Phi and Koh Lanta to the dynamic sites of the Similan and Surin National Parks, the week developed into a seamless blend of colourful reefs, schooling fish, and intricate macro life.
Day 1 – From Phuket to Koh Phi Phi National Park
We departed this adventure from Phuket with our guests from France, the UK and the USA, setting course toward the iconic Phi Phi Islands. Known for their towering limestone cliffs and emerald waters, the islands also shelter vibrant reefs teeming with life.
Anchored beneath the cliffs for the night, the atmosphere was calm and promising — a quiet beginning before the rhythm of diving took over.
Anchored beneath the cliffs for the night, the atmosphere was calm and promising — a quiet beginning before the rhythm of diving took over.
 Contrast in the blue: Elegant Moorish Idols drift past a colossal bait ball, showcasing the immense scale of marine life in the Similan Islands. |  Nature’s light show: Stunning crepuscular rays paint the sky over the North Andaman Sea, marking the end of another spectacular day of diving. |
Day 2 – Koh Phi Phi & Koh Lanta National Park
Our check dive at Bida Nok immediately set the tone. Hypselodoris purpureomaculosa added colour to the reef alongside ghostpipefish and flounders resting on the sand. A hawksbill turtle cruised by while a group of ten blacktip reef sharks patrolled the shallows. A tigertail seahorse clung delicately to the reef, while purple urchin shrimps moved among spines.
Around them, schools of five-lined snappers, yellowback fusiliers and Moorish idols filled the water column, joined by butterflyfish, surgeonfish and parrotfish grazing the reef.
Macro life was already hinting at what was to come — a richness that would only intensify as the expedition progressed.
Around them, schools of five-lined snappers, yellowback fusiliers and Moorish idols filled the water column, joined by butterflyfish, surgeonfish and parrotfish grazing the reef.
Macro life was already hinting at what was to come — a richness that would only intensify as the expedition progressed.
 Grace in the shallows: A Blacktip Reef Shark glides effortlessly past a school of snappers, captured in the pristine waters of the Similan Islands. | Renaud Liberge |  A gentle encounter: A beautiful Hawksbill Turtle navigates the vibrant coral gardens of the North Andaman Sea. | Frederique Bechet |
Moving on to Koh Lanta national park, we started with a macro treasure hunt at Koh Haa Cathedral. Noumea norba, Bornella, Phyllidiopsis striata, Halgerda bacalusia (candy halgerda) and Halgerda willeyi decorated the walls, while an Anker whip coral shrimp carrying eggs hovered delicately. Coral groupers, copperband butterflyfish, Indian sailfin tang and cleaner wrasse completed the scene.
 A splash of color: A Vermilion Grouper finds shelter in a garden of soft corals, a testament to the thriving marine life of the Similan Islands. |  Mosaic of the reef: The incredible detail and vivid colors of a Bornella anguilla nudibranch captured against a luminous yellow background. |
At Hin Daeng & Hin Muang, the pace picked up with schools of rainbow runners, giant trevallies and bluefin trevallies hunting in the blue. Batfish hovered mid-water, a hawksbill turtle passed by, and ghostpipefish blended into the reef. Jellyfish drifted through the current while juvenile emperor angelfish, bentstick pipefish, juvenile brown coral blenny, peacock mantis shrimp and longnose hawkfish kept divers scanning every corner.
Schools of fusiliers, snappers and surgeonfish added constant movement.
Schools of fusiliers, snappers and surgeonfish added constant movement.
 Underwater cathedral: Longfin Batfish glide through spectacular light rays, a serene moment captured during our deep blue exploration. |  The hunt is on: Predatory Trevally strike with lightning speed, scattering a massive bait ball in a display of raw reef energy. |
The night dive at Hin Daeng revealed Noumea sp., Hypselodoris sp., swollen bubble snails, barred-fin moray and minor moray, along with blacktail Zanzibar urchin shrimp, skeleton shrimp, tapestry shrimp and spotted reef crabs. Around them, sleeping parrotfish, hunting lionfish and active shrimps completed the nocturnal reef.
Golden hour at Koh Tarutao: The sun sets over the calm horizon as our expedition moves into the southern reaches of the Andaman Sea.
Day 3 – Koh Tarutao National Park
At 8 Mile, visibility opened wide over the pinnacle. Bentstick pipefish hovered above the reef while redbar anthias and juvenile angelfish filled the water column. Fimbriated morays peered from crevices as Spanish mackerel and great barracuda cruised past. The unusual half grouper–half barramundi added a curious highlight (same one as last trip).
Schools of fusiliers, surgeonfish and snappers moved constantly in the current.
Schools of fusiliers, surgeonfish and snappers moved constantly in the current.
 Nature’s geometry: The mesmerizing circular patterns of a juvenile Emperor Angelfish stand out against the backdrop of a rocky reef. |  Spa day on the reef: A strange looking Giant Grouper pauses at a cleaning station, allowing cleaner wrasse to attend to it in Koh Tarutao National Park. | Frederique Bechet |
Stonehenge brought a quieter atmosphere with a seahorse, Phestilla melanobrachia and flounders resting on the sand, surrounded by wrasses, damsels and butterflyfish moving between soft corals.
At Koh Taru, schools of five-lined snappers dominated the reef, joined by Phestilla melanobrachia and tiger cowries. Fusiliers, goatfish and sweetlips added movement as the light softened toward sunset.
At Koh Taru, schools of five-lined snappers dominated the reef, joined by Phestilla melanobrachia and tiger cowries. Fusiliers, goatfish and sweetlips added movement as the light softened toward sunset.
 A perfect partnership: Skunk Anemonefish find safety among the tentacles of their host, framed by the delicate beauty of a giant sea fan. |  Master of disguise: A bright yellow Tigertail Seahorse anchors itself to a colorful reef, showing off the incredible camouflage found in Koh Tarutao National Park. |
Day 4 – Koh Lanta National Park
Hin Daeng & Hin Muang once again delivered strong currents and active reefs, with schools of trevallies, fusiliers and snappers swirling around the pinnacles, alongside batfish, ghost pipefish, surgeonfish and reef predators patrolling the blue.
 Elegant residents: A duo of Redtail Butterflyfish navigates the intricate branches of a massive sea fan in the southern Andaman Sea. |  Hidden in plain sight: The remarkable camouflage of an Ghost Pipefish allows it to blend perfectly into the surrounding reef life. |
At Koh Haa Chimney, the dive shifted back to macro life with Halgerda bacalusia, Cuthona sibogae, Risbecia pulchella and ghostpipefish. Inside the structure, glassfish shimmered while outside, sweetlips, groupers, parrotfish and angelfish filled the reef.
After the dive, we began our overnight crossing toward the Similan Islands, leaving the southern reefs behind.
After the dive, we began our overnight crossing toward the Similan Islands, leaving the southern reefs behind.
 Elegant patterns: The striking purple edge and delicate spots of a Risbecia pulchella nudibranch found during Day 5 of our expedition in Similan National Park. |  Geometry in the blue: The striking ridges of a Halgerda bacalusia captured against the reef. | Renaud Liberge |
Day 5 – Similan National Park
West of Eden surprised us with a rare snaggletooth shark, alongside whitetip reef sharks cruising the reef. Pygmy pipehorse hovered delicately while McCosker’s flasher wrasse darted through the water column. The reef revealed a batwing psychedelic seaslug and a perfectly camouflaged devil scorpionfish, surrounded by butterflyfish, surgeonfish, wrasses and schools of fusiliers.
 Lighting up the reef: A stunning McCosker's flasher wrasse in full display, a highlight of our dives at Elephant Head Rock. |  Underwater art: The mind-bending colors and patterns of a Batwing psychedelic seaslug, one of the most unique macro discoveries in the Similan Islands. |
At Elephant Head Rock, blue ribbon eels waved from their burrows while octopus moved across the rocks. Three-spot angelfish and a young adult yellow boxfish stood out, while an Andaman jawfish guarded its eggs. Trevallies, snappers and sweetlips completed the dramatic setting.
North Point brought whitetip sharks, a Jenkins whipray and a juvenile Spanish dancer, alongside a wavy sap-sucking seaslug and a passing guitar shark. Schools of fusiliers and snappers added movement.
North Point brought whitetip sharks, a Jenkins whipray and a juvenile Spanish dancer, alongside a wavy sap-sucking seaslug and a passing guitar shark. Schools of fusiliers and snappers added movement.
 Double the wonder: A rare sighting of two Blue Ribbon Eels sharing a single burrow at Elephant Head Rock. |  Resting giant: A Jenkins' Whipray camouflaged against the sand, a common but always impressive resident of the North Andaman reefs. |
At Koh Bon Ridge during sunset, a whitetip reef shark moved repeatedly in and out of the reef, patrolling close to divers in a memorable encounter.
The blackwater dive revealed spear mantis shrimp larvae, squids, pelagic snails, zoea crabs, siphonophores, “pompom tail” shrimp larvae, flatworm larvae, blenny larvae, shrimp larvae, moray eel larvae and larval anemones drifting through the dark.
Blackwater once again delivered the surreal, reminding us that some of the ocean’s most fascinating life exists far from the reef.
The blackwater dive revealed spear mantis shrimp larvae, squids, pelagic snails, zoea crabs, siphonophores, “pompom tail” shrimp larvae, flatworm larvae, blenny larvae, shrimp larvae, moray eel larvae and larval anemones drifting through the dark.
Blackwater once again delivered the surreal, reminding us that some of the ocean’s most fascinating life exists far from the reef.
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From the mesmerizing patterns of macro life to the "alien" encounters of the midnight vertical migration, these seven images capture the incredible biodiversity found across our expedition through the Similan and Koh Tarutao National Parks.
Day 6 – Similan National Park
At Koh Bon Bay, orange-spotted glassy bubbles (Hyppo snails) on the reef while a school of batfish gathered in the current alongside giant trevallies and double-spotted queenfish.
 A prehistoric silhouette: The rare Bowmouth Guitarfish, also known as a Mudray, glides over the reef during an expedition to the Burma Banks. |  Silver symphony: A dense school of Longfin Batfish creates a spectacular wall of silver at the Koh Bon pinnacle. |
On Koh Bon West Ridge, an incredible encounter with a bowmouth guitar shark, alongside Spanish dancer eggs, dogtooth tuna and Spanish mackerel hunting in the blue, while fusiliers and surgeonfish filled the reef.
 Exploring the blue: A diver observes the perfect symbiosis between a clownfish and its anemone host in the Andaman Sea. |  Reef guardian: A Titan Triggerfish cruises over the coral gardens, showcasing the vibrant marine life found in Thailand's national parks. |
Koh Bon Pinnacle was alive with schools of batfish, clown triggerfish, bluefin trevallies, barracudas and yellowback fusiliers.
At Koh Tachai Pinnacle, large schools of barracudas, batfish, giant trevallies, bluefin trevallies and bigeye trevallies dominated the dive, joined by marble groupers and painted spiny lobsters hiding in the rocks.
At Koh Tachai Pinnacle, large schools of barracudas, batfish, giant trevallies, bluefin trevallies and bigeye trevallies dominated the dive, joined by marble groupers and painted spiny lobsters hiding in the rocks.
 A burst of color: This magnificent pink soft coral is a testament to the healthy, nutrient-rich currents that flow through the Similan Islands. |  Power in numbers: A massive school of barracuda creates a shimmering silver wall, a thrilling sight for any diver in the Andaman Sea. |
The night dive at Koh Tachai Reef brought hunting behaviour, with schools of checkered snappers and barracudas using our lights to hunt, while giant moray eels swam freely and blacktip sharks cruised the reef.
 Midnight patrol: A Blacktip Reef Shark cruises the reef edge under the cover of darkness, a prime example of the apex predators encountered during our night dives. |  Into the shadows: The sleek silhouette of a Blacktip Reef Shark emerges from the darkness, showcasing the thrilling wildlife sightings possible in the Andaman Sea after sunset. |
Day 7 – Surin National Park (Richelieu Rock)
Four dives at Richelieu Rock delivered a spectacular finale. White and yellow ornate ghostpipefish hovered delicately while peacock mantis shrimp and tigertail seahorses added macro highlights.
 Master of disguise: A Ghost Pipefish blends perfectly with the surrounding soft corals in the Similan Islands. |  Golden discovery: A stunning Tigertail Seahorse found tucked away in the rocky crevices of the North Andaman reefs. |
Schools of amber jacks, bigeye jacks, longnose emperors, giant trevallies, bluefin trevallies and rainbow runners filled the blue, while juvenile bridled monocle bream, baby octopus, Spanish mackerel and juvenile clown triggerfish added variety. Female Moyer’s dragonet and male Morison’s dragonet completed the scene.
 Eye of the storm: Large snappers dive through a massive bait ball, a spectacular display of predatory action in the Andaman Sea. |  The morning rush: Schools of trevally and barracuda congregate at the reef's edge as the sun breaks through the surface. |
Nudibranch diversity was exceptional, including Risbecia pulchella, Chromodoris geometrica, Glossodoris atromarginata, Hypselodoris bullocki, bicolor flabellina, Gymnodoris nigricolor and Glossodoris pallida, while flatworms such as Pseudobiceros sp7 added even more colour.
Around them, dense schools of fusiliers, snappers and glassfish wrapped the pinnacle in constant motion.
Around them, dense schools of fusiliers, snappers and glassfish wrapped the pinnacle in constant motion.
 Tornado of silver: A spectacular school of Jacks creates a living vortex in the nutrient-rich waters of the Andaman Sea. |  The crown jewel: Intense marine biodiversity flourishes over the iconic pink soft corals of Richelieu Rock. |
Day 8 – Similan National Park & Khao Lak Coast
Our final dives brought us back to Koh Tachai Pinnacle, where a hawksbill turtle, schools of batfish, bigeye jacks, barracudas and Spanish mackerel closed the trip with strong pelagic action.
 Sunset colors: A pair of Raccoon Butterflyfish, known for their distinct mask-like markings, glide past a massive sea fan in the North Andaman Sea. |  Oceanic vortex: A massive school of Bigeye Trevally creates a shimmering silhouette against the midday sun.  Master of the sand: A Kuhl’s Stingray—easily identified by its kite-like shape and blue spotting—rests on the seafloor during a daytime exploration of the reef. |
At Boonsung Wreck, a completely different atmosphere awaited. Blue-spotted Kuhl’s rays rested on the sand, honeycomb morays hid within the structure and bentstick pipefish hovered nearby. Schools of fusiliers, snappers, sweetlips and trevallies turned the wreck into a true fish haven.
 Graceful gliders: A school of bannerfish maneuvers along the reef, their long white dorsal filaments trailing behind them like ribbons in the current. |  Pattern perfection: The striking leopard-like markings of a Honeycomb Moray Eel emerge from a vibrant reef corner, a favorite find for underwater photographers. |
We then returned to Tap Lamu Pier in Khao Lak, saying goodbye after another rich and diverse journey through the Andaman Sea.
From limestone reefs to offshore pinnacles, this journey captured the changing rhythm of the Andaman Sea — where each dive revealed a new balance between movement, colour and hidden detail.
Until the next tide brings us together again — dive well, dive aware, and see you soon, fellow divers.
From limestone reefs to offshore pinnacles, this journey captured the changing rhythm of the Andaman Sea — where each dive revealed a new balance between movement, colour and hidden detail.
Until the next tide brings us together again — dive well, dive aware, and see you soon, fellow divers.
Golden hour at sea: The sun dips below the horizon, painting the sky in hues of pink and orange—the perfect end to another day of exploration in Thailand's national parks.
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