Trip Report: Mergui and Burma Banks – Special Blackwater Trip – 5th – 12th December 2025

​We departed Ranong’s Badin Pier after clearing Thai immigration, welcoming guests from Switzerland, France, Canada, the USA, Australia, Austria, the Netherlands, Macau, New Zealand, and Belgium. After a smooth Burmese immigration process in Kawthung, we set sail north through the Mergui Archipelago, a vast maze of untouched islands, mangroves, and reefs where nature still sets the rhythm.

Our first dive at South Twin Reef eased everyone into the trip. Gold-saddle rabbitfish cruised above the reef while longbarbel goatfish sifted through the sand. Vagabond and Meyer’s butterflyfish fluttered around coral heads, joined by batfish and an octopus tucked safely into its den. Schools of yellowback and neon fusiliers streamed past checkered and five-lined snappers, while coral groupers and ringtail surgeonfish patrolled the hard coral slopes. Cleaner wrasses darted between passing fish, completing the scene.

Dives two and three at North Twin Reef brought more action. Blackfin barracudas formed tight schools in the blue, cuttlefish hovered above the reef, and scorpionfish blended perfectly into the background. Bicolor parrotfish grazed noisily, lionfish hovered motionless, and tiny gobies and blennies peeked out from coral cracks as moon wrasses and sixline wrasses zigzagged through the reef.
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As night fell, we launched our first blackwater dive, and it delivered instant magic. A marlin appeared out of the darkness, hunting right along the dive line. Sleeper lobsters drifted by clutching salps, spearing mantis shrimps flashed their raptorial arms, and jellyfish, comb jellies, and larvaceans filled the water column. Larval flounders, sea butterflies, crab larvae, flying squid, mahi-mahi, golden trevallies, and even a wandering moray eel made this an unforgettable first plunge into the deep pelagic night.

​We spent the entire day at Black Rock, one of the jewels of the Mergui Archipelago. Rising steeply from the depths, this exposed seamount is famous for big fish, strong currents, and surprises.

Dives one, two, and three were blessed with oceanic Manta rays gliding effortlessly around the divers, looping back again and again as if curious. Great barracudas, cobias, and massive schools of blackfin barracudas filled the blue, while yellowback and neon fusiliers shimmered around the rock. Chromodoris nudibranchs added color to the reef, octopuses hid among the boulders, and schools of jacks surged past. Among them swam schools of giant trevallies, bluefin trevallies, golden trevallies, and bigeye trevallies, with the golden trevallies appearing to be in full mating display. A school of blacktip trevallies (Caranx heberi), an unusual sight, swept past the reef.”

The sunset dive revealed a different world. Clark’s anemonefish guarded their eggs fiercely, surrounded by anemone crabs, squat shrimps, marble shrimps, and banded boxer shrimps. Octopuses crept across the reef, Durban dancing shrimps waved from crevices, schools of black surgeonfish passed by, and African pompano cruised through the fading light. Porcupinefish, map puffers, bullet head parrotfish, and powder-blue surgeonfish rounded off the scene.
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Some divers opted for another blackwater dive, encountering pelagic seahorses, larval tuna, pencil squid, larval triggerfish, mini jacks sheltering inside salps, and post-larval African pompano drifting silently through the darkness.

We explored Three Islets, diving between Shark Cave, Submarine, and Square.
At Submarine, a bamboo shark rested under an overhang while cleaner pipefish and orange-spotted pipefish hovered nearby. Blue-spotted ribbontail rays glided across the sand, batfish cruised by, and the reef came alive with moon wrasses, bullethead parrotfish, yellowback fusiliers, damselfish, and map puffers.Shark Cave revealed tomato and Clark’s anemonefish guarding their homes, anemone crabs waving from their tentacles, and white-eye moray eels peering from the shadows. Wrasses repeatedly attacked sergeant majors guarding their eggs, while schools of golden trevallies, yellow-lined fusiliers, and even a passing wahoo added excitement.
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At Square, we found tiger-tail seahorses, orange-spotted pipefish, yellowtail barracudas, giant trevallies hiding in cracks, golden trevallies, and batfish drifting calmly in the blue.
After the final dive, we set sail west toward the Burma Banks, a remote chain of offshore seamounts rising abruptly from deep water, known for big sharks, strong currents, and true blue-water diving.

Our first dive at Row Bank delivered classic Burma Banks scenery. Adult and juvenile nurse sharks rested on the sand, ringtail and epaulette surgeonfish grazed nearby, and honeycomb moray eels peeked from coral heads. Golden rabbitfish, two-spot butterflyfish, and oriental sweetlips mingled with small coral groupers, cleaner wrasses, bullethead parrotfish, juvenile angelfish, and cleaning shrimps.
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After the dive, the weather began to build. For safety reasons, we made the decision to leave the banks early and head back toward the shelter of the Mergui Archipelago. Spirits stayed high onboard, with time to relax, review photos, and enjoy the ride back through calmer waters.

Back at Western Rocky, the first two dives at the Cave and Eagle’s Rock offered rich macro life. Octopuses, harlequin shrimps, Spanish mackerel, Bornella nudibranchs, twin chromodoris, and colorful soft corals filled the walls. Schools of snapper and fusiliers passed by, while butterflyfish, angelfish, wrasses, and damselfish kept the reef buzzing.

The third dive and sunset at Sea Fan Forest brought cuttlefish, stonefish, octopuses, blacktail barracudas, and flowing schools of neon and yellowback fusiliers. Coral groupers, moon wrasses, parrotfish, butterflyfish, triggerfish, and clouds of damselfish swirled around the massive sea fans.

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That night, some divers slipped back into the dark for another blackwater dive, encountering sea snakes, salps, crab larvae, snapper larvae, cornetfish larvae, paper nautilus octopuses, sleeper lobsters, mantis shrimps, amphipods, and countless drifting creatures carried by the current.

An early morning dive at Sea Fan Forest set the tone for the day. Cuttlefish hovered over the reef, stonefish lay perfectly camouflaged on the bottom, and octopuses moved between coral heads. Peacock mantis shrimps guarded their burrows while yellow and brown trumpetfish drifted vertically along the sea fans. Red lionfish and clearfin lionfish hunted in the shadows, joined by devil scorpionfish resting motionless. Schools of yellowback and neon fusiliers streamed past, accompanied by lunar wrasses, bullethead parrotfish, and clouds of blue-green chromis.
We then returned to Western Rocky for three rich dives.At the Cave, ghost pipefish swayed gently next to the wall, while blunt decorator crabs, white-spotted hermit crabs, and cleaning shrimps occupied every ledge. Giant moray eels watched from deep inside the cave, sharing the space with honeycomb moray eels. Nudibranchs such as leopard chromodoris and blue dragons added color, while Moorish idols cruised slowly past. The reef was busy with porcupinefish, map puffers, clown triggerfish, blueface angelfish, emperor angelfish, raccoon butterflyfish, and threadfin butterflyfish weaving through the coral.At Eagle Rock, the action moved into the blue. Spanish mackerel cut through schools of jacks, including giant trevallies, bluefin trevallies, and bigeye trevallies. Schools of yellowback and neon fusiliers wrapped the rock, mixed with five-lined snappers and yellow-lined snappers. Devil scorpionfish sat patiently on the bottom while several octopuses were spotted mating in the shallows. The reef itself was alive with moon wrasses, sixline wrasses, damselfish, skunk anemonefish, Clark’s anemonefish, coral groupers, honeycomb groupers, blennies peeking from holes, angelfish, butterflyfish, and triggerfish cruising between boulders.
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The final dive at the Islets was a macro lover’s dream. Harlequin shrimps danced on sea stars, twin chromodoris and blue dragons crawled across the reef, and pipefish hovered close to soft corals. Around them swam a colorful mix of damselfish, fairy wrasses, parrotfish, butterflyfish, juvenile angelfish, rabbitfish, and small snappers, bringing the day to a perfect close.

Our last dive of the trip took place at Dendro’s Peak, and it delivered a spectacular finale. Two giant marble rays glided effortlessly above the reef, while cuttlefish were seen mating on the top of the pinnacle, the male flashing intense patterns and colors to protect his female from rivals. Large schools of jacks and mackerel swept through the blue, joined by giant trevallies, bluefin trevallies, and golden trevallies. Yellowback and neon fusiliers formed dense clouds over the reef, constantly on the move.

On the reef itself, bird wrasses, moon wrasses, and sixline wrasses darted between coral heads, while coral groupers and honeycomb groupers patrolled their territories. Bullethead parrotfish and bicolor parrotfish grazed noisily, surrounded by damselfish guarding their nests. Skunk anemonefish and Clark’s anemonefish hovered above their anemones, and triggerfish cruised past, including yellow-margin triggerfish and titan triggerfish.
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After surfacing, we set course back toward Kawthung for Burmese immigration, shared a final goodbye beer onboard, and finally returned to Ranong to re-enter Thailand. A fitting end to an intense and unforgettable journey through the Mergui Archipelago, the Burma Banks, and the deep pelagic world of blackwater diving.