Exploring Thailand’s Underwater National Treasures
As the sun rose over Ranong, we welcomed an enthusiastic group of divers from the USA, France, Brasil, and Switzerland aboard the MV Smiling Seahorse. Our journey would take us through some of Thailand’s most iconic national parks—from Surin and Similan to Lanta and Tarutao—each with its own unique seascape and underwater wonders. Spirits were high as we set a course for the famed Surin Islands to begin our underwater adventure. All pictures on this blogpost were taken by our distinguished guests.

Three Trees delivered calm water and stunning white sand patches covered in garden eels. A porcupine stingray and blue-spotted ray swept by, while above us schools of fusiliers and snappers moved in synchronized waves. Curious trumpetfish hovered and gobies danced along the sandy slopes.
Elephant Head Rock was majestic as always. We drifted through its cavernous swim-throughs, surrounded by walls adorned with giant sea fans and hunting giant moray eels. A white-tip shark slipped by, and above us an eagle ray soared across the sunbeams. We caught sight of a mature yellow boxfish before it tucked into a crevice, while blue-lined groupers and bannerfish hovered near the edges of the boulders.

The sunset dive was full of movement and macro life. Helmet crabs and decorator crabs scuttled across the reef while zebra moray eels and common morays hunted along the slopes. Nudibranchs—chromodoris fidelis, annulata, risbecia, and geminus—dotted the rocks like confetti, with bornella anguilla curling through the soft corals.

At Koh Taru, baby yellow fusiliers filled the reef, flashing like lightning. A baby yellow boxfish stole hearts with its wobbling swim, while a large star puffer looked on with sleepy eyes. Indian Ocean walkman scorpionfish and banded pipefish made rare appearances to round off the day.

​Our journey began in Ranong, where our international guests—this time hailing from France, Austria, and the Philippines—stepped aboard the MV Smiling Seahorse, their eyes alight with excitement. After clearing Thai immigration, we crossed the border into Kawthoung, Myanmar, where the rhythmic stamping of passports signaled the official start of our voyage into one of the last untouched marine frontiers: the breathtaking Mergui Archipelago. It was a pleasure welcoming back some good friends and creating new friendships this week.

The ocean greeted us gently at High Rock, our check dive site, where the clear waters hinted at the wonders lying beneath the surface. Silver ribbons of yellowtail barracudas spiraled gracefully around us, mingling with yellowback fusiliers weaving effortlessly through the current. A shy moray eel peeked out from its crevice, while a solitary thornback boxfish hovered calmly nearby. Hidden among the branches of a gorgonian fan, a tiger tail seahorse played a game of underwater hide-and-seek. Vibrant nudibranchs—tiny explosions of color—adorned the reef like living confetti, as schools of butterflyfish flitted past, as curious about us as we were about them.

At Three Islets, the magic only deepened. Shark Cave pulsed with life: a proud adult yellow tiger tail seahorse clung steadfastly to a coral branch, while banded stick pipefish slithered gracefully through the rubble below. Along the rocky surfaces, Chromodoris and Flabellina nudibranchs performed their delicate, colorful dance. Above, fusiliers—blue-lined, yellow-lined, and every shade in between—formed a shimmering curtain that rippled across the reef. A sleek wahoo darted through the school like a silver arrow, while angelfish and parrotfish painted the scene with bold strokes of tropical color.

At Square, the underwater action showed no sign of slowing. Yellowstripe trevallies and longnose emperors darted through shimmering clouds of glassfish, while brassy and golden trevallies cruised along the reef’s edge like vigilant sentinels. Amid the commotion, tiger tail seahorses clung calmly to coral branches, unbothered by the lively currents. Butterflyfish and wrasses wove through the midwater, adding intricate layers to the reef’s silent symphony.

At Submarine, gentle currents allowed us to drift effortlessly alongside schools of rainbow runners, blacktip fusiliers, and golden dash fusiliers. A marble ray glided like a shadow over the sandy bottom, barely disturbing the drowsy goatfish resting below. Nearby, damselfish fiercely guarded their nests, while a curious trumpetfish trailed us, blending amusingly with our dive gear.

After a surface interval filled with laughter and fresh fruit, we stepped ashore at the quaint village of Khun Pi Lar. Its white-sand beach and serene Buddha temple offered a peaceful contrast to the vibrant underwater world.

As night fell, we returned to Shark Cave, now transformed into a nocturnal wonderland. Sweetlips slumbered beneath ledges, decorator crabs scuttled by in bizarre camouflage, and a ghost pipefish twirled in our torchlight. A Chromodoris geminus glowed like a living jewel, illuminating the darkness with its fluorescent brilliance.

We began the next day with Roe Bank, where nurse sharks rested languidly on the sandy bottom, surrounded by shimmering schools of silver sweetlips. Nearby, a marlin breached near the boat—an electrifying moment of pure ocean magic. The fish schools were immense: scissortail fusiliers, yellowback fusiliers, and black-and-white snappers surged like living tides. Giant sweetlips and redfin butterflyfish hovered near coral heads, accompanied by inquisitive triggerfish and a vibrant assortment of wrasses.

At Rainbow Bank, our third dive brought us face-to-face with a swirling vortex of bigeye trevallies—a mesmerizing underwater tornado. Nurse sharks cruised by silently, while a mangrove whipray materialized from the gloom like a gliding UFO. Amid the bustle of sweetlips and giant snappers, we spotted elegant pairs of bannerfish fluttering gracefully, and clouds of anthias painted the coral outcrops in vivid orange hues.

Our sunset dive was nothing short of exhilarating. One group encountered a bold and curious bull shark, while nurse sharks hovered in the twilight shadows. Honeycomb moray eels slithered between coral heads, and territorial triggerfish patrolled the sandy slopes, fiercely guarding their nests. Pufferfish drifted by slowly, like whimsical balloons suspended in the deep.

Meanwhile, others descended into the inky blackness for a blackwater dive—a surreal journey into the unknown. From the depths rose tiny post-larval creatures: flounders, squid, even a sea elephant, their translucent forms glowing under our lights like alien visitors in a dreamlike ballet from the abyss.

The next morning, Roe Bank welcomed us once more. It was so good, it was worth coming back! Dogtooth tuna sliced through vast shoals of fusiliers, their speed a blur against the swirling backdrop. Marble rays lay half-buried in the sand, only to lift off with a graceful flap, vanishing into the blue. We wound our way around boulders teeming with surgeonfish, while massive potato groupers watched from the shadows, still and imposing.

At Coral Bank, the excitement continued. Nurse sharks cruised alongside us, and another bull shark made a brief but thrilling appearance. Towering schools of yellow dot fusiliers and surgeonfish filled the water column, while rainbow runners shot through them like silver missiles. Below, groupers, triggerfish, and curious blennies darted among the coral rubble, each corner revealing new life.

Silvertip Bank brought our adventure to a spectacular finale. Nurse sharks patrolled in lazy circles, marble rays soared effortlessly overhead, and a majestic Napoleon wrasse glided past with quiet authority. Curtains of fusiliers shimmered like underwater rainbows, momentarily parting to reveal damselfish, groupers, and sergeant majors weaving through the colorful chaos.

We returned to Seafan Forest under crystal-clear conditions, the visibility offering a perfect window into the reef’s vibrant life. Fusiliers flowed like living rivers across the coral landscape, pursued by sleek great barracudas and darting rainbow runners. A pharaoh cuttlefish shimmered with ever-changing colors as it glided by, while a stonefish lay perfectly still, masterfully disguised among the reef. A proud tiger tail seahorse clung delicately to a sea fan, and nearby, a devil scorpionfish nestled between sponge and coral, its spiny silhouette barely detectable.

The adventure continued at Eagle Rock and Western Rocky Cave. Schools of batfish drifted gracefully overhead, five-line snappers pulsed across the reef in synchronized bursts, and twinstripe fusiliers streamed past like underwater arrows.
Chromodoris nudibranchs were abundant, their vibrant bodies accompanied by delicate, ribbon-like spirals of freshly laid eggs. Sponge snails peeked from their porous homes, while giant moray eels and fimbriated eels slinked through the crevices. A bright red frogfish, bold and still, posed patiently for photos—one nestled beneath the arch, the other tucked against the rocky wall like a secret waiting to be discovered.

We returned once more to Seafan Forest, and the magic continued. Nudibranchs spiraled their ribbon-like eggs onto the reef, stonefish vanished into their surroundings with expert camouflage, and schools of yellowback fusiliers pulsed rhythmically over coral heads like golden currents. Back at Eagle Rock and Western Rocky, we were delighted to find our familiar pair of giant frogfish—still motionless, still mesmerizing—surrounded by a kaleidoscope of reef life. Damselfish fiercely guarded their patches of eggs, while curious puffers hovered nearby, inspecting our bubbles with wide-eyed fascination.

Our final dive brought us to Dendro’s Pinnacle—and what a farewell it was. Visibility stretched endlessly as we drifted through clouds of five-line snappers and golden trevally. Yellowtail barracudas shimmered like blades in the distance.
​We were treated to the sight of not one, but two dazzling Chromodoris species--annulata and reticulata—while a graceful orange-spotted pipefish waved a quiet goodbye from the coral.

While these closures may seem inconvenient, they are crucial for the long-term health of Thailand’s marine ecosystems.
​​
Why Are Marine Parks Temporarily Closed?
Seasonal closures serve several critical purposes, balancing conservation efforts with sustainable tourism.

1. Protecting Wildlife and Biodiversity
Many marine species depend on undisturbed habitats for breeding and nesting.
Seasonal closures help safeguard their survival by minimising human interference. For instance:
Sea turtles return to the exact beach where they were born to lay their eggs. However, if they detect human activity or disturbances, they may abandon their nesting attempt, which can significantly impact their population.
Fish populations flourish in quiet, healthy reefs, but excessive diving activity can create significant stress for marine species. Furthermore, diver's bubbles, and boat engines contribute to a disruptive noise pollution, that may affect migration patterns. 
Migratory birds rely on secluded islands for rest during their long journeys. They are highly sensitive to human interaction, which can cause them to abandon crucial stopover sites, leading to exhaustion and lower survival rates.


​2. Coral Reef Regeneration 
Coral reefs are among the most delicate ecosystems on the planet. Activities like diving, snorkeling, and boat traffic can damage these fragile habitats. Seasonal closures allow corals to regenerate, improving their health and resilience. This ensures a more vibrant experience for visitors once the parks reopen.

3. Safety
This period corresponds to the monsoon season, with strong winds coming from the west and big waves forming between the Indian continent and Thailand's west coast. While navigating might be possible on some days, it is usually not safe to do so.

1. Explore Alternatives Near Phuket
Phuket Thailand’s largest island, is an excellent starting point for exploring marine attractions. During the off-season, consider visiting:
- Racha Islands: These islands offer some of the best diving conditions in Thailand, even during the rainy season.
- Koh Yao Noi and Koh Yao Yai: Located in Phang Nga Bay, these islands remain serene and welcoming throughout the year.
​
2. Discover Year-Round Destinations 
While the Andaman Sea's national parks may be closed, other diving locations remain open all year round in the gulf of Thailand: 
- Koh Tao: A diver’s destination known for its calm waters and cheap diving, Koh Tao is the perfect place to refine your skills. With a variety of diving schools, you can take courses in underwater photography, technical diving, freediving, or even work towards becoming a dive Master. The island's fun atmosphere and affordable training options make it an ideal destination for divers of all levels.
- Koh Samui and Koh Phangan: Slightly bigger, these tropical islands offer excellent snorkeling opportunities, stunning beaches for relaxation, and diverse wildlife encounters. Beyond their natural beauty, they also boast a vibrant nightlife scene, making them an appealing destination for both adventure seekers and those looking to unwind.