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Trip Report | North Andaman | 7th to 14th April, 2026

24/4/2026

The MV Smiling Seahorse liveaboard boat cruising through the blue waters of the North Andaman Sea, Thailand, during a dive expedition.

The ocean doesn’t follow a plan — it sets the pace.

Over the course of this North Andaman expedition, each dive unfolded with its own rhythm, from granite boulder fields to fish-packed pinnacles, where currents, schools and encounters constantly reshaped the experience.

Day 1 – Departure from Khao Lak to the Similan Islands

We departed from Tap Lamu Pier in Khao Lak with our guests from France, heading north toward the Similan Islands. Calm seas and a soft golden light set the tone as we settled into life on board, preparing for the days of diving ahead.

A crew member named Boom driving a blue and white inflatable dinghy on calm waters in Similan National Park.

Boom Driving the Dinghy | Denis Cadon

Divers gathered around a table on a liveaboard deck for a sunset dive briefing in Thailand.

Guests and staff go over the dive plan for the next site in Similan National Park.

Day 2 – Similan National Park

At Shark Fin Reef, the first dive was the perfect warm up with a classic Similan landscape of submerged granite formations. Two-tone dartfish hovered above the sand while a hawksbill turtle cruised by. Clown triggerfish and a whitetip reef shark added movement, while dogtooth tuna patrolled the blue. On the reef, Gymnodoris (lemon gymnodoris), Caloria indica, six-striped soapfish, andaman sweetlips and juvenile chiseltooth wrasse appeared among schools of blue-and-gold fusiliers and surgeonfish. Our divers were also able to recover a knot of abandoned fishing gear that was floating at the surface- we always give back to the ocean when we can.

A Hawksbill sea turtle swimming through deep blue water in the Similan Islands, Thailand.

A graceful Hawksbill sea turtle captured mid-glide through the pristine blue waters of the Similans. | Denis Cadon

A Giant Moray Eel peering out from a colorful coral reef structure in the North Andaman Sea.

This Giant Moray Eel found a perfect hiding spot among the colorful corals and granite boulders of North Andaman. | Denis Cadon

A colorful Caloria indica nudibranch with orange, blue, and white cerata crawling on a red sponge in the North Andaman Sea.

The vibrant colors of a Caloria indica nudibranch stand out against the red reef sponges during a macro dive in the North Andaman. | Denis Cadon

At Boulder City, the energy picked up. The “gang” of bluefin trevallies and longnose emperors hunted through a dense school of batfish and barracuda. Around the reef, bignose unicornfish, humpback unicornfish and bluespine unicornfish cruised effortlessly, some stopping to show off their colours to a potential mate. Macro life revealed long-snouted crinoid shrimp, commensal crinoid shrimp, false cleaner wrasse, Midas blenny, Smith’s fang blenny and both adult and juvenile blue-lined angelfish.

A tiny Long-Snouted Crinoid Shrimp (Allogalathea elegans) perfectly camouflaged within the feathered arms of a crinoid.

Hidden in plain sight: The intricate patterns of a Long-Snouted Crinoid Shrimp help it blend seamlessly with its host in the North Andaman. | Denis Cadon

A large coral head decorated with colorful, spiraling Christmas Tree Worms (Spirobranchus giganteus) on a reef in the Similan Islands.

A large brain coral head decorated with colorful, spiraling Christmas Tree Worms (Spirobranchus giganteus) on a reef in the Similan Islands.

At Hideaway, the dive slowed down with octopus, Glossodoris cincta, garden eels and squat shrimps tucked into the reef. A psychedelic batwing slug stood out among the colours, while fusiliers, butterflyfish and surgeonfish filled the water column.

The day ended with a sunset dive at Honeymoon Bay, where we found a brave longfin comet fish hiding inside the reef, a Jenkins whipray rested on the sand, and dragonets darted between coral heads. Marbled grouper, bluefin trevally, octopus, moray eels and another psychedelic batwing slug completed a calm and atmospheric dive, with brown tangs grazing quietly in the fading light.

A wide-angle view of a diverse coral reef featuring table corals, soft corals, and a diver in the background in the North Andaman Sea.

A thriving underwater garden: Table corals and vibrant soft corals create a stunning backdrop for divers exploring the healthy reefs of the Similan Islands. | Denis Cadon

A tiny Psychedelic Batwing Sea Slug (Sagaminopteron psychedelicum) with intricate white and green patterns on a reef in Thailand.

A true macro treasure: The rare and stunning Psychedelic Batwing Sea Slug is a bucket-list find for many divers in the North Andaman. | Denis Cadon

A close-up of an octopus peeking out from a small crevice within a hard coral reef structure.

Keeping a watchful eye: An octopus masterfully blends into the coral crags of the Similan Islands, waiting for the perfect moment to move. | Denis Cadon

A bright yellow Longnose Butterflyfish swimming past pink soft coral trees on a reef in Similan National Park.

A splash of color: This Longnose Butterflyfish stands out beautifully against the lush soft coral gardens of the Similan Islands. | Denis Cadon

A dark Comet Fish with white spots tucked into a rocky crevice on a coral reef in the North Andaman Sea.

Finding the shy ones: A stunning Comet Fish displays its starry patterns while hiding among the reef crags of North Andaman. | Denis Cadon

Day 3 – Similan National Park

At Deep Six, strong currents brought action. A whitetip reef shark passed by, alongside a green turtle and bluefin trevallies. Macro highlights included Glossodoris cincta, baby Moridilla brocki, clown triggerfish and a striking blue dragon.

A colorful Glossodoris cincta nudibranch with a distinctive dark border crawling across a sandy seabed in Thailand.

A macro highlight: This Glossodoris cincta nudibranch showcases its intricate patterns while traversing the white sands of the Similan Islands. | Denis Cadon

Two bright orange anemonefish peeking out from the protective tentacles of their host sea anemone in the North Andaman Sea.

A classic reef scene: Curious anemonefish dart between the swaying tentacles of their home in Similan National Park. | Denis Cadon

A Spearing Mantis Shrimp peeking out from its burrow in the reef floor, showing its large, complex eyes.

Peer into the burrow: The incredible eyes of a Spearing Mantis Shrimp watch carefully as we explore the reef floor in North Andaman. | Denis Cadon

At West of Eden, the reef was alive with detail. Spearing mantis shrimps and squat shrimps occupied the substrate, while McCosker’s flasher wrasse flickered in the water column. Schools of emperors, hawksbill and green turtles, batwing psychedelic seaslugs, multibar pipefish and Andaman jawfish created a rich and varied dive. Fusiliers, snappers and parrotfish filled every layer.

At Elephant Head Rock, dramatic swim-throughs revealed ribbon eels, Andaman jawfish, Glossodoris cincta and bluestreak gobies. Schools of trevallies, sweetlips and fusiliers added movement to the rugged topography.

Massive orange and yellow gorgonian sea fans clinging to a rocky reef wall in the North Andaman Sea.

A wall of life: Stunningly large gorgonian sea fans stretch out into the current along the granite walls of the Similan Islands. | Denis Cadon

Three Moorish Idols with their distinctive yellow, black, and white bands swimming vertically against a deep blue reef backdrop.

Elegance in motion: A trio of Moorish Idols showcases their long dorsal filaments while cruising the healthy reefs of Similan National Park. | Denis Cadon

A massive, shimmering school of transparent Glassfish swarming around a colorful coral reef wall in the North Andaman Sea.

Underwater fireworks: A dense school of Glassfish shimmers like silver as they flow over the vibrant soft corals and sea fans of Similan National Park. | Denis Cadon

Later, we stepped ashore at Island Number 8, where a short climb led us to the iconic viewpoint overlooking Donald Duck Bay — a sweeping panorama of turquoise water framed by granite boulders, offering a rare moment to take in the Similan Islands from above.

Four smiling guests standing on a large granite boulder overlooking the turquoise bay and white sand beach of Similan Island No. 8.

Making memories at the top: Our guests enjoying the panoramic views from the famous Donald Duck Rock viewpoint. | Denis Cadon

High-angle scenic view of the crystal-clear turquoise waters and lush tropical greenery of Donald Duck Bay in the Similan Islands.

Perfection in blue: The iconic view of Donald Duck Bay, where white sands meet the vibrant reefs of Similan National Park. | Denis Cadon

The night dive at Turtle Rock brought intense activity. Snappers hunted in the beams of our lights while skeleton shrimps, decorator crabs, ornate sapsucking slugs, tiger cowries, whip coral shrimps and anemone hermit crabs covered the reef. A spearing mantis shrimp enjoyed an all you can eat shrimp buffet in our torchlight while soft coral ghost gobies, clearfin lionfish, feather duster worms, Gosliner flatworms, Harpiliopsis shrimp, Hyman’s flatworm, bicolor flabellina and Glossodoris cincta completed the scene.

A large Map Pufferfish swimming over a dark reef alongside a school of small silver fish during a night dive in the Similan Islands.

A large pufferfish glides through the darkness, surrounded by shimmering baitfish on a healthy reef in Similan National Park. | Denis Cadon

A close-up of diverse hard and soft corals illuminated during a night dive in the Similan Islands, Thailand.

The reef transforms after dark, revealing the intricate textures and deep colors of the hard corals in Similan National Park. | Denis Cadon

A detailed macro shot of a Glossodoris cincta nudibranch with its signature dark, ruffled border on a rocky reef.

Macro perfection: This Glossodoris cincta nudibranch stands out against the rugged reef floor of the North Andaman Sea. | Denis Cadon

Day 4 – Similan National Park

At North Point, the dive opened with a balanced mix of pelagic movement and reef life. Dogtooth tuna cruised past in the blue while a turtle moved calmly along the reef. Schools of barracuda held their position in the current, creating a steady backdrop of motion.

Closer to the reef, the scene became more detailed: fringelip blenny peeked from small crevices, juvenile lionfish drifted cautiously between coral heads, and sand lizardfish rested motionless on the bottom. Schools of lunar fusiliers and neon fusiliers streamed across the reef, joined by striped surgeonfish grazing steadily, while butterflyfish and damselfish filled the shallower sections.

A scuba diver named Pascal exploring the deep blue waters of Similan National Park, Thailand.

Into the abyss: Pascal takes in the incredible visibility and deep blue hues that make diving in the Similans world-famous. | Denis Cadon

A wide-angle view of diverse corals and tropical fish, including a Monocle Bream, on a sunlit reef in the North Andaman Sea.

Life on the reef: A Monocle Bream swims past a fan-shaped coral structure during a sun-drenched afternoon dive in North Andaman. | Denis Cadon

At Christmas Point, the energy shifted into a true hunting scene. Bluefin trevallies and longnose emperors formed the core of the action, working together with rainbow runners in tight formations — a classic “Christmas tree” moment as they moved across the reef in coordinated bursts. Around them, schools of fusiliers and snappers reacted instantly, compressing and expanding in response to the pressure, constantly reshaping the water column. Wrasses and parrotfish pecked at the reef, weaving through the chaos.

A vibrant Checkerboard Wrasse showing its neon green, pink, and blue patterns while swimming over a rocky reef in the Similan Islands.

A kaleidoscope of color: This Checkerboard Wrasse puts on a brilliant display as it patrols the sunlit reefs of the North Andaman Sea. | Denis Cadon

At Three Trees, the landscape opened into sandy patches and coral bommies, creating a more spacious and atmospheric dive. A Kuhl’s stingray rested half-buried while the glassfish filled every crevice of the reef and nearby bommies.

In the blue, a tornado of barracuda briefly formed, tightening into a spinning column before slowly dispersing again — a fleeting but striking moment. Oriental sweetlips hovered near coral heads, while yellowfin emperor and brown-marbled grouper stayed close to structure.

Large barrel sponges hosted sea fans growing along their sides, with spotted garden eels scattered across the sand. Yellowmargin triggerfish guarded their nests, adding bursts of territorial energy, while bignose unicornfish cruised above.

Barrel Sponge Denis Cadon Andaman Scuba Diving Liveaboard Thailand

A titan of the reef: This ancient Giant Barrel Sponge adds a dramatic splash of red to the underwater landscapes of Similan National Park. | Denis Cadon

The final dive at Koh Bon brought us fully back into the blue. A Napoleon wrasse appeared out of the current, followed by dogtooth tuna cutting across the reef. Schools of barracuda, batfish and rainbow runners moved constantly through the site, with bluefin trevallies weaving between them.

A scuba diver floating on the surface with an orange signaling buoy, waiting for a boat pickup in the deep blue waters of the Andaman Sea.

Mission accomplished: A diver signals the boat after an incredible drift dive through the crystal-clear waters of Similan National Park. | Denis Cadon

A large Map Pufferfish (Arothron mappa) swimming over a rocky reef next to a pale pink soft coral tree in Thailand.

Reef residents: A distinctive Map Pufferfish glides past vibrant soft corals during a dive in the North Andaman Sea. | Denis Cadon

Day 5 – Koh Bon & Koh Tachai

At Koh Bon Pinnacle, the dive delivered one of the highlights of the trip: a bull shark appearing briefly in the blue, powerful and unmistakable. A hawksbill turtle hid under an overhang, while yellowback fusiliers filled the water column. Bluefin trevallies hunted actively, and a cluster of Spanish dancer eggs clung to the reef. Batfish hovered mid-water while a guitarfish rested on the sand, almost blending into the seabed. Brown-marbled groupers stayed close to the reef, completing the scene.

A tiny green Sap-Sucking Slug (Costasiella sp.) camouflaged against algae on a reef in Thailand.

Hidden beauty: A macro look at a Sap-Sucking Slug, a master of disguise in the lush underwater gardens of the Similan Islands. | Denis Cadon

A massive orange gorgonian sea fan standing prominently against the deep blue water of the North Andaman Sea.

Majestic structures: This expansive sea fan highlights the healthy, current-swept walls found throughout the Similans. | Denis Cadon

A vibrant school of yellow snappers swimming beneath bright pink soft coral trees on a rocky reef.

A riot of color: Yellow snappers create a stunning contrast against the pink soft corals in Similan National Park. | Denis Cadon

A large Spiny Lobster peeking out from its rocky shelter on a coral reef in the Andaman Sea.

Reef guardians: A Spiny Lobster keeps a watchful eye from the safety of its coral crevice in North Andaman. | Denis Cadon

At Koh Tachai Pinnacle, schools of batfish gathered in impressive numbers, mixing with giant trevallies, bluefin trevallies and bigeye trevallies. Brown-marbled groupers moved between boulders while schools of bluestreak fusiliers, neon fusiliers and yellowback fusiliers streamed across the pinnacle.
The following dive at Koh Tachai Pinnacle brought great barracudas patrolling the edges, alongside more bluefin trevallies and giant trevallies. We spotted some lobster hiding in the cracks as longnose emperors moved confidently around us. A Juvenile Spanish dancer and Hypselodoris maculosa added colour to the substrate as Boer's batfish and a group of teenage longfin batfish hovered in the current, creating a layered mid-water scene. Spotted hypselodoris appeared along the reef, reinforcing the macro diversity.

A large, silver Batfish swimming toward the camera, perfectly framed by the sun's rays in the deep blue waters of the Similan Islands.

A moment of grace: This curious Batfish drifts effortlessly through the crystal-clear waters of Similan National Park, illuminated by the midday sun. | Denis Cadon

A small, bright orange and red sea star resting on a rocky reef floor in the Similan Islands.

Spotted on the seafloor: A vibrant red sea star adds a pop of color to the granite underwater landscapes of Similan National Park. | Denis Cadon

A powerful Giant Trevally (Caranx ignobilis) swimming through the deep blue water of the North Andaman Sea.

Power in the blue: A majestic Giant Trevally patrols the current-swept reefs, showcasing the impressive predator life of North Andaman. | Denis Cadon

The night dive at Koh Tachai Reef was intense from start to finish. Blacktip reef sharks were present from the first minute to the last, constantly cruising through the lights. Anemone hermit crabs, blunt decorator crabs and ornate sapsucking slugs dotted the reef, while an unidentified flatworm added another mysterious element to the dive.

Nighttime adrenaline: Encountering Blacktip Reef Sharks under the cover of darkness at Koh Tachai is a highlight of the Andaman experience. | Denis Cadon

Day 6 – Surin National Park

A snorkeler's head visible in the water nestled between large granite boulders at Surin National Park.

Hidden coves: Exploring the dramatic rocky coastlines and pristine waters of Surin National Park. | Denis Cadon

A snorkeler wearing a bright orange life vest and mask floating in clear turquoise water at the surface.

Surface wonders: The vibrant turquoise waters of the Surin Islands offer world-class snorkeling right from the boat. | Denis Cadon

At Hin Kong, macro life took center stage. Cadlinella ornatissima, Robastra gracilis, squat shrimps, porcelain crabs and Hyman’s flatworms were scattered across the reef, turning the dive into a slow and detailed exploration. During our surface intervals, we also had lovely snorkelling excursions to the coast of these stunning islands.

A dark Hyman's Flatworm with an orange-gold ruffled border crawling over a textured, sandy reef floor in the Similan Islands.

Elegance in miniature: The striking ruffled edges of a Hyman's Flatworm create a beautiful contrast against the rugged seabed of Similan National Park. | Denis Cadon

At Yellow Rock, we witnessed a full colour spectrum in our encounters. Spotted hypselodoris, Hypselodoris bullocki, allied cowrie and bicolor flabellina stood out against the reef. A juvenile shaded batfish tried to blend in nearby, while a pygmy seahorse remained perfectly camouflaged. Silver Andaman sweetlips added contrast, moving slowly along the reef.

A Juvenile Shaded Batfish with a tall, black body and vibrant orange trim swimming near a colorful reef crevice in the Similan Islands.

A rare find: The striking silhouette and bold orange highlights of a Juvenile Shaded Batfish stand out against the red sponges of Similan National Park.

At Torinla, two Napoleon wrasses stole the show — one large female and an impressive, massive male cruising slowly across the site, completely unbothered by divers. A hawksbill turtle munched away at the corals, equally unimbressed by the divers while a tiny juvenile pufferfish tried to hide in the sand on the reef’s edge.

A tiny, vibrant yellow Cadlinella ornatissima nudibranch with pink-tipped nodules crawling on a textured reef in Thailand.

Small wonders: This brightly colored Cadlinella ornatissima nudibranch is a prized find for macro photographers in Similan National Park.

A detailed shot of a Lionfish with its striped body and venomous fins displayed, swimming near red sponges on a rocky reef.

Elegant predator: A Lionfish displays its ornate fins as it patrols the healthy, sponge-covered reefs of the North Andaman Sea.

A Scribbled Filefish with neon blue patterns swimming over a colorful coral reef, with a school of fusiliers in the background.

Electric patterns: The Scribbled Filefish stands out with its intricate blue markings against the diverse reef life of Similan National Park. | Denis Cadon

A macro shot of a spotted Porcelain Crab tucked safely among the stinging tentacles of a sea anemone.

Symbiotic safety: A tiny Porcelain Crab finds shelter within the protective tentacles of an anemone in the North Andaman Sea. | Denis Cadon

The night dive at Ao Pakkad delivered one of the strongest macro moments of the trip. Seven harlequin shrimps were found across the site, alongside Flabellina exoptata, Glossodoris atromarginata, complex marble shrimps, Conus geographus and blacktail Zanzibar urchin shrimp. Around them, file fish, crabs, shrimps and nocturnal reef life created a dense and vibrant night scene.

A pair of Harlequin Shrimp (Hymenocera picta) with pink and blue spots feeding on a red sea star on a rocky reef.

A rare macro find: Harlequin Shrimp display their intricate patterns while perched on a sea star in the Similan Islands. | Denis Cadon

A vibrant purple and orange Flabelina exoptata nudibranch clinging to a delicate hydroid against a dark background.

Neon of the reef: The striking colors of a Flabelina exoptata nudibranch stand out in the crystal-clear waters of the North Andaman Sea. | Denis Cadon

Day 7 & 8 – Richelieu Rock

Six dives at Richelieu Rock brought a grand finale to the trip, combining dense fish life with outstanding macro diversity.
Nudibranchs were everywhere: Spotted hypselodoris, ornate sapsucking slug, Chromodoris geometrica, Chromodoris rufomarginata, Chromodoris annulata, Chromodoris reticulata, Risbecia pulchella, Glossodoris atromarginata, Halgerda tesselata mating, Cadlinella ornatissima, bicolor flabellina and ridged Dermatobranchus.

A bright yellow and black patterned Reticulidia suzanneae nudibranch crawling on a textured reef wall in Thailand.

Intricate patterns: The bold, geometric design of the Reticulidia suzanneae nudibranch is a stunning sight on the reefs of Similan National Park. | Denis Cadon

A pair of Doriprismatica atromarginata nudibranchs with ruffled black and white borders resting next to a white egg ribbon on a reef.

The cycle of life: A Doriprismatica atromarginata nudibranch beside its delicate egg mass, captured in the rich waters of the North Andaman Sea. | Denis Cadon

A vibrant Tiger Egg Cowrie (Cuspivolva tigris) with bold orange and black stripes nestled among the branches of a pink soft coral in Thailand.

Hidden gems: The brilliant stripes of a Tiger Egg Cowrie create a stunning visual contrast against the delicate textures of the North Andaman reefs. | Denis Cadon

Two ornate ghostpipefish hovered delicately in the current, while a thorny seahorse remained anchored to the reef. Harlequin shrimps added flashes of colour, and a juvenile yellow boxfish drifted nearby.

A yellow Ornate Ghost Pipefish (Solenostomus paradoxus) camouflaged against a colorful reef wall in the Similan Islands.

Masters of disguise: The intricate details of an Ornate Ghost Pipefish make it one of the most sought-after sightings for divers in Similan National Park.

A pair of Harlequin Shrimp (Hymenocera picta) with their distinctive blue and pink spots tucked into a rocky crevice on a Thailand reef.

Vibrant reef residents: A beautiful pair of Harlequin Shrimp, known for their striking patterns and unique diet, found during a dive in the North Andaman Sea.

A large, dark Giant Moray Eel resting its head near a vibrant coral outcrop featuring pink and orange sponges.

Reef sentinels: A massive Moray Eel peers out from a colorful coral head in the pristine waters of Similan National Park. | Denis Cadon

In the blue, the full “gang” was present: bluefin trevallies, giant trevallies, rainbow runners, amber jacks and longnose emperors hunting continuously. They even teamed up with a giant moray eel near the bottom of the pinnacle for a hunt on our last dive. Schools of barracudas circled the pinnacle, while longfin batfish hovered elegantly in mid-water.

A group of large Emperor fish, including a Longnose Emperor, swimming through dark, shaded reef areas in the Similan Islands.

"The Gang": A group of formidable Longnose Emperors patrol the deep recesses of the reef in Similan National Park. | Denis Cadon

Four White Eyed Moray Eels (Gymnothorax thyrsoideus) sharing a single rocky crevice on a vibrant reef in Thailand.

Crowded quarters: A group of White Eyed Moray Eels peeking out from their rocky home in Similan National Park. | Denis Cadon

A Zebra Moray Eel (Gymnomuraena zebra) displaying its distinctive dark and light striped pattern as it emerges from a reef.

Striking patterns: The unique, banded appearance of a Zebra Moray Eel captured in the rich waters of the North Andaman Sea. | Denis Cadon

Moray eels were well represented with zebra morays and white-eye morays moving between crevices, completing a site that once again delivered both scale and detail in perfect balance.

A scuba diver, Dive Guide Julien, swimming through a massive, swirling bait ball of small silver fish in the deep blue waters of the Andaman Sea.

Surrounded by life: Dive Guide Julien is engulfed by a spectacular swirling bait ball, a common and breathtaking sight in the vibrant waters of the Similan Islands. | Denis Cadon

A bright orange Tomato Anemonefish (Amphiprion frenatus) with a signature black spot swimming beside its host anemone.

Bold and beautiful: The striking orange and black of a Tomato Anemonefish stands out among the swaying tentacles of a healthy reef in the Similan Islands. | Denis Cadon

A colorful Peacock Mantis Shrimp (Odontodactylus scyllarus) peering out from its sandy burrow under a reef ledge.

Master of the reef: Known for its incredible eyes and powerful punch, the Peacock Mantis Shrimp is a colorful wonder of the North Andaman Sea. | Denis Cadon

The final evening brought everyone together on the upper deck for our traditional BBQ, a well-earned moment after days of diving. The air was warm, the sea calm, and the boat gently rocking under a sky full of stars. Between grilled food, shared stories and laughter, the atmosphere slowly shifted from relaxed to festive, and before long, the music took over and the deck turned into a dance floor. A perfect way to close the trip — somewhere between celebration and that quiet feeling of not quite wanting it to end.

Day 8 - Return to Ranong

After these final dives, we made our way back toward Ranong, closing another North Andaman expedition filled with contrasts — from fast-paced pelagic encounters to intricate macro discoveries — exactly the kind of balance that makes this region so unique.
Some trips are measured in sightings. Others in the rhythm they leave behind.
This one offered both — from powerful encounters in the blue to the smallest details hidden in the reef.
Until the next tide brings us together again — see you soon, fellow divers.

Four scuba divers--Dive Guide Julien, Dive Guide Joy, Denis, and Pascal--posing in full gear on the deck of a dive boat at sunset.

The dream team: Ending an incredible journey in the Andaman Sea with Dive Guides Julien and Joy, alongside Denis and Pascal.

A close-up underwater selfie of Pascal and Denis wearing scuba masks and regulators during a dive.

Deep blue memories: Pascal and Denis sharing one last look at the stunning reefs of Similan National Park.

Photos Taken by Denis Cadon

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Trip report | Thailand | South & North Andaman Expedition, 29th March – 5th April 2026

15/4/2026

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A wide sunset view over the calm Andaman Sea with rocky islands on the horizon, featuring a

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.

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.

Several Moorish Idols swimming in front of a massive, swirling silver bait ball in the deep blue Andaman Sea.

Contrast in the blue: Elegant Moorish Idols drift past a colossal bait ball, showcasing the immense scale of marine life in the Similan Islands.

A dramatic sunset over the ocean with orange and pink crepuscular rays fanning out across a darkening sky near rocky islets.

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.

A Blacktip Reef Shark (Carcharhinus melanopterus) swimming over a rocky reef accompanied by a small school of yellow snappers in the Andaman Sea.

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 close-up view of a Hawksbill Turtle (Eretmochelys imbricata) swimming gracefully over a colorful coral reef in Thailand.

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 bright orange Vermilion Grouper resting among white and pink soft corals with a school of small reef fish in the blue Andaman Sea.

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.

A macro close-up of a mosaic-patterned Bornella anguilla nudibranch with orange-tipped rhinophores crawling on a bright yellow sponge.

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.

A group of Longfin Batfish (Platax teira) swimming through cathedral-like sunbeams in the clear blue waters of the Andaman Sea.

Underwater cathedral: Longfin Batfish glide through spectacular light rays, a serene moment captured during our deep blue exploration.

A school of predatory Trevally fish diving into a massive, dense bait ball of smaller fish in the open ocean.

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.

A tranquil sunset over the Andaman Sea with dark rocky formations in the foreground, marking the start of Day 3 in Koh Tarutao National Park.

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.

A vibrant juvenile Emperor Angelfish with concentric electric blue and white circular patterns swimming near a sea urchin.

Nature’s geometry: The mesmerizing circular patterns of a juvenile Emperor Angelfish stand out against the backdrop of a rocky reef.

A large, mottled Giant Grouper with its mouth open while a small cleaner wrasse performs its duties on a colorful 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.

Two pink Skunk Anemonefish (Amphiprion akallopisos) hovering above their host anemone with a large, intricate sea fan in the background.

A perfect partnership: Skunk Anemonefish find safety among the tentacles of their host, framed by the delicate beauty of a giant sea fan.

A vibrant yellow Tigertail Seahorse (Hippocampus comes) with dark markings gripping a branch of pink soft coral.

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.

A pair of Redtail Butterflyfish (Chaetodon collare) swimming in front of a large, complex orange sea fan on a healthy reef.

Elegant residents: A duo of Redtail Butterflyfish navigates the intricate branches of a massive sea fan in the southern Andaman Sea.

A highly camouflaged Ghost Pipefish (Solenostomus paradoxus) hovering vertically near a sea fan on a vibrant reef wall.

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.

A close-up of a Risbecia pulchella nudibranch, featuring a creamy body with yellow spots and a distinct purple ruffled border.

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.

A macro image of a Halgerda bacalusia nudibranch, featuring a white body with a network of orange-yellow ridges and dark-tipped gills.

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.

A colorful male McCosker's flasher wrasse (Paracheilinus mccoskeri) displaying vibrant blue, orange, and red colors while swimming among smaller reef fish in the deep blue.

Lighting up the reef: A stunning McCosker's flasher wrasse in full display, a highlight of our dives at Elephant Head Rock.

A macro close-up of a Batwing psychedelic seaslug (Sagaminopteron psychedelicum) featuring intricate patterns of purple, orange, and green on a soft coral background.

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.

Two vibrant male Blue Ribbon Eels (Rhinomuraena quaesita) extending from the same burrow with mouths open against a rocky reef background.

Double the wonder: A rare sighting of two Blue Ribbon Eels sharing a single burrow at Elephant Head Rock.

A large Jenkins' Whipray (Pateobatis jenkinsii) resting on the sandy seafloor near a rocky outcrop in the clear waters of the Similan Islands.

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.

A transparent, ribbon-like larval eel drifting against a pitch-black background.

A small, transparent juvenile squid with visible internal organs and orange pigment spots.

A delicate, translucent blue sea butterfly shell drifting in the open ocean at night.

A highly detailed glass squid with vibrant red and purple chromatophores shimmering against the dark water.

A bell-shaped, translucent zoanthid larva of the Zoantharia subclass floating in the open ocean at night during a blackwater dive.

The identification for the left-hand image in image_574af0.png has been updated to reflect this specific larval stage encountered during your blackwater exploration. Left: Larval Anemone Alt Text: A translucent larval anemone with long, delicate tentacles radiating outward, captured against a solid black background during a blackwater dive.

A translucent Phronima amphipod glowing with blue and gold hues as it drifts through the dark water column.

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 Bowmouth Guitarfish (Rhina ancylostoma) swimming over a rocky reef accompanied by a diverse school of tropical fish in clear blue water.

A prehistoric silhouette: The rare Bowmouth Guitarfish, also known as a Mudray, glides over the reef during an expedition to the Burma Banks.

A large, shimmering school of silver Longfin Batfish (Platax teira) gathered around a coral pinnacle in the Similan Islands.

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.

A silhouette of a scuba diver hovering in clear blue water above a large sea anemone hosting a bright orange clownfish.

Exploring the blue: A diver observes the perfect symbiosis between a clownfish and its anemone host in the Andaman Sea.

A large, colorful Titan Triggerfish (Balistoides viridescens) swimming over a hard coral reef under bright, sunny surface conditions.

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.

A large, bright pink soft coral (Dendronephthya) blossoming on a rocky reef, surrounded by small tropical fish in clear blue water.

A burst of color: This magnificent pink soft coral is a testament to the healthy, nutrient-rich currents that flow through the Similan Islands.

A dense, swirling school of chevron barracuda swimming in the open blue water near the ocean surface.

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.

A Blacktip Reef Shark (Carcharhinus melanopterus) swimming swiftly over a dark reef at night, with its distinctive black-tipped dorsal fin visible against the dark water.

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.

A macro shot of a spiny Ghost Pipefish (Solenostomus paradoxus) hovering near vibrant pink soft corals.

Master of disguise: A Ghost Pipefish blends perfectly with the surrounding soft corals in the Similan Islands.

A close-up of a bright yellow Tigertail Seahorse (Hippocampus comes) anchored to the reef substrate.

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.

A large, swirling bait ball of small silver fish being pursued by several large red snappers in clear blue water.

Eye of the storm: Large snappers dive through a massive bait ball, a spectacular display of predatory action in the Andaman Sea.

A dynamic underwater scene featuring schools of trevally and barracuda silhouetted against the bright surface sun over a coral reef.

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.

A massive, dense school of silver Jacks (Caranx) swirling in clear blue water over a dark reef edge.

Tornado of silver: A spectacular school of Jacks creates a living vortex in the nutrient-rich waters of the Andaman Sea.

A diverse school of reef fish, including snappers and emperors, swimming over a lush garden of pink soft corals.

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.

A pair of vibrant yellow and black Raccoon Butterflyfish (Chaetodon lunula) swimming past a large, intricate red gorgonian sea fan on a steep reef wall.

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.

A dense, circular school of Bigeye Trevally silhouetted against the bright surface sun in deep blue water.

Oceanic vortex: A massive school of Bigeye Trevally creates a shimmering silhouette against the midday sun.

A Kuhl's Stingray (Neotrygon kuhlii), also known as a Bluespotted Maskray, resting on the sandy seafloor near soft corals in clear daylight.

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.

A large school of longfin bannerfish (Heniochus acuminatus) swimming together against a dark reef slope in deep blue water.

Graceful gliders: A school of bannerfish maneuvers along the reef, their long white dorsal filaments trailing behind them like ribbons in the current.

A vibrant macro shot of a Honeycomb Moray Eel (Gymnothorax favagineus) with its mouth slightly open, tucked into a colorful coral crevice surrounded by small orange fish.

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.

A vibrant orange sun setting over the calm ocean and distant islands, viewed from the deck of a dive boat.

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.

Photos by: Franck Fogarolo, Frederique Bechet and Renaud Liberge

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Trip Report | North Andaman | 7th to 14th April, 2026

Day 1 – Departure from Khao Lak to the Similan Islands

Day 2 – Similan National Park

Day 3 – Similan National Park

Day 4 – Similan National Park

Day 5 – Koh Bon & Koh Tachai

Nighttime adrenaline: Encountering Blacktip Reef Sharks under the cover of darkness at Koh Tachai is a highlight of the Andaman experience. | Denis Cadon

Day 6 – Surin National Park

Day 7 & 8 – Richelieu Rock

Day 8 - Return to Ranong

Trip report | Thailand | South & North Andaman Expedition, 29th March – 5th April 2026

Day 1 – From Phuket to Koh Phi Phi National Park

Day 2 – Koh Phi Phi & Koh Lanta National Park

Day 3 – Koh Tarutao National Park

Day 4 – Koh Lanta National Park

Day 5 – Similan National Park

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

Day 7 – Surin National Park (Richelieu Rock)

Day 8 – Similan National Park & Khao Lak Coast

Photos by: Franck Fogarolo, Frederique Bechet and Renaud Liberge

The Smiling Seahorse Diving Blog

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The Smiling Seahorse

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Trip Report | North Andaman | 7th to 14th April, 2026

Day 1 – Departure from Khao Lak to the Similan Islands

Day 2 – Similan National Park

Day 3 – Similan National Park

Day 4 – Similan National Park

Day 5 – Koh Bon & Koh Tachai

Nighttime adrenaline: Encountering Blacktip Reef Sharks under the cover of darkness at Koh Tachai is a highlight of the Andaman experience. | Denis Cadon

Day 6 – Surin National Park

Day 7 & 8 – Richelieu Rock

Day 8 - Return to Ranong

Trip report | Thailand | South & North Andaman Expedition, 29th March – 5th April 2026

Day 1 – From Phuket to Koh Phi Phi National Park

Day 2 – Koh Phi Phi & Koh Lanta National Park

Day 3 – Koh Tarutao National Park

Day 4 – Koh Lanta National Park

Day 5 – Similan National Park

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​

Day 7 – Surin National Park (Richelieu Rock) ​

Day 8 – Similan National Park & Khao Lak Coast ​

Photos by: Franck Fogarolo, Frederique Bechet and Renaud Liberge

The Smiling Seahorse Diving Blog

Authors

Categories

Archives

See also...

The Smiling Seahorse

Our dive cruises

More information

Day 6 – Similan National Park

Day 7 – Surin National Park (Richelieu Rock)

Day 8 – Similan National Park & Khao Lak Coast