Batwing Sea Slug | Itai Grisaru
Some trips lean toward pelagic action. Others toward patient macro exploration. This North to South Andaman crossing gave us both.
This North-to-South Andaman expedition took us through four marine national parks — Surin, Similan, Koh Lanta and Tarutao — before finishing in Phuket. A true cross-section of Thailand’s Andaman Sea.
This trip became a beautiful contrast between “the big” and “the small” — manta encounters, shark sightings and hunting trevallies on one side… and delicate nudibranchs, shrimps and ghost pipefish on the other.
This North-to-South Andaman expedition took us through four marine national parks — Surin, Similan, Koh Lanta and Tarutao — before finishing in Phuket. A true cross-section of Thailand’s Andaman Sea.
This trip became a beautiful contrast between “the big” and “the small” — manta encounters, shark sightings and hunting trevallies on one side… and delicate nudibranchs, shrimps and ghost pipefish on the other.
 Big Eye Trevally Swimming Into a Bait Ball  Shore Visits on the Dinghy |  A View From the Surface  Big Eye Trevally Hunting |
Day 1 – From Ranong to Surin National Park
We welcomed our divers from Buddy Divers Israel in Ranong and began our journey southward. The route would take us through Surin National Park first, then down to the Similan Islands, further south to Koh Lanta and Tarutao, before heading back north toward Phuket.
A true Andaman traverse...
A true Andaman traverse...
Day 2 – Surin National Park
Our check dive at Koh Chi Reef offered calm conditions and crystal-clear visibility. The Surin Islands, home to the Moken sea nomads, are known for their gentle sandy slopes and vibrant coral gardens.
False anemonefish and Clark’s anemonefish hovered over magnificent sea anemones while moray eels peered from coral heads. Schools of five-lined snappers moved in tight formation above the reef. Blue-barred parrotfish and bullethead parrotfish grazed over staghorn coral and honeycomb coral formations.
Cleaner wrasse, moon wrasse and sixline wrasse worked busily along the reef, while hawksbill turtles glided past. Slender Roboastra, orange-spotted Chelidonura, sea cucumbers, black diadema sea urchins and feather stars dotted the seabed.
False anemonefish and Clark’s anemonefish hovered over magnificent sea anemones while moray eels peered from coral heads. Schools of five-lined snappers moved in tight formation above the reef. Blue-barred parrotfish and bullethead parrotfish grazed over staghorn coral and honeycomb coral formations.
Cleaner wrasse, moon wrasse and sixline wrasse worked busily along the reef, while hawksbill turtles glided past. Slender Roboastra, orange-spotted Chelidonura, sea cucumbers, black diadema sea urchins and feather stars dotted the seabed.
 Anemonefish |  Turtle  Reef Fish | Itai Grisaru |
Then came Richelieu Rock.
If there is a place where “big versus macro” truly coexist, it is here.
The “gang” was in full hunting mode: giant trevallies, bluefin trevallies, bigeye trevallies and massive schools of rainbow runners sweeping through clouds of glassfish. Yellowtail and chevron barracudas cruised the perimeter. A shy black manta passed in the blue for one lucky group.
If there is a place where “big versus macro” truly coexist, it is here.
The “gang” was in full hunting mode: giant trevallies, bluefin trevallies, bigeye trevallies and massive schools of rainbow runners sweeping through clouds of glassfish. Yellowtail and chevron barracudas cruised the perimeter. A shy black manta passed in the blue for one lucky group.
Feeding Frenzy at Richelieu Rock
 "The Gang" Hunting at Richelieu Rock |  Black Oceanic Manta Ray |
White-eye, fimbriated and giant moray eels filled nearly every crack. Yellowback fusiliers and two-spot fusiliers swirled above schools of five-lined snappers.
Meanwhile, macro lovers were glued to the rock: Chromodoris annulata, Cuthona sibogae, Chromodoris geometrica, slender Roboastra, and delicate thorny seahorse and a couple of harlequin shrimps hiding into pink and purple soft corals covering the pinnacle.
Meanwhile, macro lovers were glued to the rock: Chromodoris annulata, Cuthona sibogae, Chromodoris geometrica, slender Roboastra, and delicate thorny seahorse and a couple of harlequin shrimps hiding into pink and purple soft corals covering the pinnacle.
 Thorny Seahorse |  Flabellina Nudibranch | Itai Grisaru |
The night dive shifted the mood completely. Glossodoris atromarginata, orange-tip Flabellina, Moridilla brocki, Bicolor Flabellina, reef crabs, blunt decorated crabs, squat shrimps and banded boxer shrimps emerged. Morays hunted actively and cuttlefish drifted through the beam of torches.
Big by day. Intricate by night.
Big by day. Intricate by night.
 Harlequin Shrimp Pair | Itai Grisaru |  Nudibranch Laying Eggs | Itai Grisaru |
Day 3 – Similan National Park
Koh Tachai Pinnacle greeted us with explosive fish action. Yellowback, neon, manylined and blue-and-gold fusiliers streamed in the current.
Massive marble groupers and coral groupers rested along granite slopes. Peacock groupers, steephead parrotfish, blue-barred parrotfish and bullethead parrotfish grazed constantly.
Moon wrasse, bird wrasse and pastel green wrasse flashed between coral heads. Batfish hovered in the blue. Blueface angelfish and royal angelfish added vibrant colour.
Hard coral bommies, table corals and giant sea fans framed the scene.
Massive marble groupers and coral groupers rested along granite slopes. Peacock groupers, steephead parrotfish, blue-barred parrotfish and bullethead parrotfish grazed constantly.
Moon wrasse, bird wrasse and pastel green wrasse flashed between coral heads. Batfish hovered in the blue. Blueface angelfish and royal angelfish added vibrant colour.
Hard coral bommies, table corals and giant sea fans framed the scene.
 Guest Photographer Extraordinaire Itai Grisaru |  Lionfish |
At Koh Tachai Reef, blacktip reef sharks cruised the shallow reef edge while halgerda tesselata rested near sand patches. Common porcupinefish and yellowdot pufferfish hovered near cracks guarded by giant moray eels. Durban dancing shrimps decorated coral heads.
Koh Bon Ridge delivered octopus encounters, Haminoea cymbalum, batfish and oriental sweetlips over powder-blue surgeonfish and lined surgeonfish. Glassfish filled the bay in thick clouds.
Blackwater that night brought a completely different universe: purple back squid, lizardfish post-larvae, pyrosomes, tuna larvae, lionfish larvae, butterflyfish post-larvae, triggerfish larvae, coral eggs, female paper nautilus, veligers, crab zoea, tozuma shrimp and even an immortal jellyfish.
Koh Bon Ridge delivered octopus encounters, Haminoea cymbalum, batfish and oriental sweetlips over powder-blue surgeonfish and lined surgeonfish. Glassfish filled the bay in thick clouds.
Blackwater that night brought a completely different universe: purple back squid, lizardfish post-larvae, pyrosomes, tuna larvae, lionfish larvae, butterflyfish post-larvae, triggerfish larvae, coral eggs, female paper nautilus, veligers, crab zoea, tozuma shrimp and even an immortal jellyfish.
 Squid in Blackwater |  Larval Triggerfish in Blackwater |
Female Paper Nautilus
 Immortal Jellyfish in Blackwater |  Larval Lionfish in Blackwater |
Day 4 – Similan Islands
Three Trees started with garden eels swaying in sandy flats and blue-spotted Kuhls rays feeding nearby. Massive barrel sponges crowned granite boulders.
One group spotted a guitar shark — a ray-like shark species combining traits of both families — gliding along the seabed.
Schools of yellowback fusiliers, neon fusiliers and scissortail fusiliers mixed with five-lined snappers and yellow saddle goatfish. Great barracuda and dogtooth tuna patrolled deeper edges.
Elephant Head Rock delivered blue ribbon eels, adult boxfish, giant trevallies and juvenile clown triggerfish among swim-throughs framed by antler coral and leather coral.
One group spotted a guitar shark — a ray-like shark species combining traits of both families — gliding along the seabed.
Schools of yellowback fusiliers, neon fusiliers and scissortail fusiliers mixed with five-lined snappers and yellow saddle goatfish. Great barracuda and dogtooth tuna patrolled deeper edges.
Elephant Head Rock delivered blue ribbon eels, adult boxfish, giant trevallies and juvenile clown triggerfish among swim-throughs framed by antler coral and leather coral.
 Juvenile Clown Triggerfish |  Blue Ribbon Eel | Itai Grisaru |
West of Eden gave us Thorunna chromodoris, psychedelic batwing seaslug, hairy shrimp and mating octopus pairs. Giant blue-lined pufferfish hovered above the reef alongside copperband butterflyfish and regal angelfish.
 Batwing Sea Slug |  Hairy Shrimp |
Day 5 – Koh Lanta National Park
Hin Mueang opened with dramatic walls covered in red soft coral and sea fans. Glossodoris hikuerensis and its eggs decorated the slopes. Trevallies and rainbow runners swept through yellowback and neon fusilier schools.
Coral groupers, blacktip groupers and brown marble groupers hid among hard coral ridges. Powder-blue surgeonfish, velvet surgeonfish and Indian mimic surgeonfish crossed the current.
Hin Daeng amplified the “big” feeling: batfish, Napoleon wrasse, giant trevallies and dogtooth tuna patrolled the vertical reef. Ghost pipefish hovered delicately near soft corals.
Butterflyfish including threadfin butterflyfish, raccoon butterflyfish and Meyer’s butterflyfish added colour, while emperor angelfish and semicircle angelfish patrolled mid-water.
Macro remained strong with nudibranchs scattered across the slopes.
Blackwater that evening revealed comb jellies hosting isopods and pelagic gastropods drifting through the darkness.
Coral groupers, blacktip groupers and brown marble groupers hid among hard coral ridges. Powder-blue surgeonfish, velvet surgeonfish and Indian mimic surgeonfish crossed the current.
Hin Daeng amplified the “big” feeling: batfish, Napoleon wrasse, giant trevallies and dogtooth tuna patrolled the vertical reef. Ghost pipefish hovered delicately near soft corals.
Butterflyfish including threadfin butterflyfish, raccoon butterflyfish and Meyer’s butterflyfish added colour, while emperor angelfish and semicircle angelfish patrolled mid-water.
Macro remained strong with nudibranchs scattered across the slopes.
Blackwater that evening revealed comb jellies hosting isopods and pelagic gastropods drifting through the darkness.
 Larval Crab in Blackwater |  Gastropod and Amphipod in Blackwater |
Ready for Blackwater Diving!
 Pelagic Worm in Blackwater |  Amphipod on a Comb Jelly |
Day 6 – Koh Tarutao National Park
Eight Mile, near the Malaysian border, offered a striking yellow and pink coral-covered pinnacle dotted with sea urchins. Schools of jacks and rainbow runners hovered above.
Juvenile semicircle angelfish, juvenile blue-ringed angelfish, juvenile emperor angelfish and regal angelfish contrasted beautifully with the darker reef backdrop.
Juvenile semicircle angelfish, juvenile blue-ringed angelfish, juvenile emperor angelfish and regal angelfish contrasted beautifully with the darker reef backdrop.
Vibrant Soft Coral
Stonehenge showcased purple and pink soft corals clinging to sculpted rock formations. A thorny seahorse clung to gorgonians. Yellow-edge moray eels and giant moray eels guarded crevices while tomato anemonefish and masked porcupinefish completed the reef tableau.
Koh Sawang at sunset displayed titan triggerfish, giant blue-lined pufferfish, regal angelfish, coral groupers and schools of fusiliers under golden light.
Blackwater revealed larval tonguefish, gastropods mating, pelagic worms and drifting crustaceans.
Koh Sawang at sunset displayed titan triggerfish, giant blue-lined pufferfish, regal angelfish, coral groupers and schools of fusiliers under golden light.
Blackwater revealed larval tonguefish, gastropods mating, pelagic worms and drifting crustaceans.
 Pelagic Worm in Blackwater |  Larval Tonguefish in Blackwater | Itai Grisaru |
Mating Sea Butterflies in Blackwater
 Larval Snail in Blackwater |  Larval Shrimp in Blackwater |
Day 7 – Koh Lanta
Hin Mueang again delivered ghost pipefish, juvenile emperor angelfish, halgerda tesselata and African wrasse.
Hin Daeng brought double-spotted queenfish, barracudas, needlefish and more dogtooth tuna, alongside orange-spotted pipefish and lobsters hiding under ledges.
Hin Daeng brought double-spotted queenfish, barracudas, needlefish and more dogtooth tuna, alongside orange-spotted pipefish and lobsters hiding under ledges.
 Ghost Pipefish | Itai Grisaru |  Halgerda Tessellata Nudibranch | Itai Grisaru |
Koh Haa Cathedral provided classic cavern drama: whip coral shrimp, banded sea snake, cleaner pipefish, twin goniobranchus, Cuthona sibogae, Glossodoris hikuerensis, and dark-margin glossodoris with eggs.
At Koh Haa Chimney, a banded sea snake guarded the interior cave while Bornella anguilla waited at the exit. Skeleton shrimps and ornate sapsucking slugs clung to soft coral branches.
The day ended with our traditional BBQ under the stars.
At Koh Haa Chimney, a banded sea snake guarded the interior cave while Bornella anguilla waited at the exit. Skeleton shrimps and ornate sapsucking slugs clung to soft coral branches.
The day ended with our traditional BBQ under the stars.
 Bornella Anguilla Nudibranch | Itai Grisaru |  Sap Sucking Slug | Itai Grisaru |
Happy Group on BBQ Night!
Day 8 – Koh Phi Phi National Park
Koh Bida Nok welcomed us with blacktip reef sharks cruising the reef. Tiger-tail seahorses and ghost pipefish clung to soft corals. Schools of yellow-lined snappers and yellowback fusiliers swirled around healthy hard coral formations.
Eagle Ray at Shark Point | Video Taken by Dive Guide Vélika
At Shark Point, a not-so-shy eagle ray joined our final dive, swimming alongside schools of yellowback fusiliers, five-lined snappers, yellowtail and chevron barracudas. Cadlinella ornatissima rested quietly on the reef.
 Happy Divers |  Cadlinella Ornatissima Nudibranch | Itai Grisaru |
From pelagic mantas and hunting trevallies to delicate nudibranchs and larval life, this trip perfectly balanced the immense and the microscopic.
Another North to South Andaman journey comes to an end — and once again, the Smiling Seahorse delivered both spectacle and subtlety in equal measure.
Until next time.
Photo by Franck Fogarolo & Itai Grisaru
Another North to South Andaman journey comes to an end — and once again, the Smiling Seahorse delivered both spectacle and subtlety in equal measure.
Until next time.
Photo by Franck Fogarolo & Itai Grisaru
A View of Koh Haa
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