South and North Andaman Sea, Thailand: March 23rd to 31st, 2025. Whale Shark Expedition

For this Whale Shark Expedition, we were thrilled to welcome aboard the M/V Smiling Seahorse a diverse group of divers from Romania, France, the USA, and Australia. Adding to the excitement, we were joined by Josh Johnson, a marine biologist specializing in whale shark conservation. Based in Koh Tao, Josh is a graduate of the University of Plymouth’s BSc Ocean Science and Marine Conservation program.

Josh shared fascinating insights into whale shark biology, ecology, and conservation:
“Although they are the largest fish in the world, they remain one of the least studied sharks globally, especially in Thai waters. With so much still to learn about them, it is crucial to explore new methods for monitoring their migration patterns and feeding hotspots. This allows us to implement the best conservation strategies to protect these gentle giants.”

Setting sail from Phuket on March 23rd, we first explored Koh Lanta National Park and Koh Tarutao National Park for three days before heading north to discover the wonders of the Similan and Surin National Parks. Each of these marine sanctuaries is a jewel of the Andaman Sea, boasting a unique blend of stunning underwater landscapes, thriving marine life, and vibrant coral ecosystems.
•    Koh Lanta National Park is renowned for its dramatic limestone formations and rich marine biodiversity.
•    Koh Tarutao, the largest national park in the Andaman, remains a pristine paradise with spectacular reefs and abundant pelagic life.
•    The Similan Islands, world-famous for their breathtaking granite boulders and crystal-clear waters, offer incredible diving experiences with flourishing coral gardens and deep pinnacles.
•    Surin National Park, home to the legendary Richelieu Rock, features one of Thailand’s most spectacular dive sites, teeming with marine life and a prime location for large pelagic encounters.

This unforgettable expedition combined breathtaking scenery, exceptional dives, and invaluable knowledge, leaving us all with a deeper appreciation for whale sharks and their conservation.

Our check dive at Koh Ha Lagoon provided a smooth and scenic introduction to the trip. Among the coral bommies, we spotted a perfectly camouflaged Ornate Ghost Pipefish, swaying gently with the current, while a curious Coral Grouper patrolled its reef territory. Schools of Yellowback Fusiliers darted through the water, accompanied by striking Emperor Angelfish, adding bursts of vibrant color to the scene.

In the afternoon and evening, we explored Hin Mueang and Hin Daeng, where the reefs were teeming with life. A Clown Frogfish, perfectly still and expertly blended into a sponge, caught our attention. Nearby, pairs of Ornate Ghost Pipefish hovered delicately in the water. Overhead, Red-Toothed Triggerfish swirled in mesmerizing formations, while Giant Trevallies patrolled the reef in search of prey. Schools of Rainbow Runners flashed by in unison, and among the hard corals, we admired a striking Peacock Grouper and a Blue-Barred Parrotfish lazily grazing.

​The morning began at Hin Paad Mile, where Giant Trevallies moved in synchronized schools, their silver bodies flashing as they sliced through the water. Beneath a coral ledge, a massive Potato Grouper rested, watching us with a slow, deliberate gaze. Around us, schools of Bengal Snappers and Blue-and-Gold Fusiliers shimmered, creating a breathtaking display of color and motion.

At Stonehenge, the highlight was a perfectly camouflaged Tigertail Seahorse, delicately gripping onto a sea fan. Nearby, an Indian Walkman lay in wait on the sand, its intricate fins blending seamlessly with the ocean floor.

We ended the day with a mesmerizing Blackwater dive, drifting in the darkness while witnessing an extraordinary parade of tiny pelagic creatures rising from the depths–baby squids, larval fish, and even a tiny pelagic seahorse making a rare appearance.

Before crossing to the Similan Islands, we completed one last dive at Hin Mueang, where we revisited our Clown Frogfish and discovered a few new additions to the scene. Moorish Idols glided effortlessly above the reef, a school of Twinstripe Fusiliers darted between coral formations, and a well-camouflaged Bearded Scorpionfish lay hidden among the rocks, waiting patiently for unsuspecting prey.

Our dive at Shark Fin Reef welcomed us with a breathtaking spectacle of marine life—schools of Lunar Fusiliers swirled around us in a dazzling display, while Parrotfish crunched noisily on the reef, shaping the underwater landscape with every bite.

At West of Eden, we encountered a playful Octopus, shifting colors in a mesmerizing dance before our eyes. A Rock Mover Wrasse skillfully flipped coral rubble in search of hidden prey, while a Psychedelic Batwing Seaslug nestled discreetly in a crevice, adding a splash of vibrant color to the reef.

At Elephant Head Rock, the current carried us effortlessly past Giant Trevallies hunting in the blue, while a pair of Sweetlips hovered serenely beneath an overhang. In a sandy patch, a White Tip Reef Shark lay motionless, completely undisturbed by our presence.

We ended the day with a captivating night dive at Turtle Rock, where Basket Stars unfurled their intricate arms to feed, and Decorator Crabs, masterfully disguised with sponges and algae, scuttled stealthily across the seabed.

Xmas Point welcomed us with a vibrant display of reef life—from the dazzling flashes of Blue Striped Snappers to the sleek, steady glide of a Barracuda lurking in the distance.

At 3 Trees, a Blue Spotted Stingray lay half-buried in the sand, perfectly camouflaged, while a massive Potato Grouper loomed near the coral formations, surveying its domain.

Meanwhile, Koh Bon Pinnacle and West Ridge were alive with movement, as schools of Rainbow Runners and Longnosed Emperors wove effortlessly through the currents, creating a mesmerizing underwater ballet.

Returning to Koh Bon Pinnacle and West Ridge, we were greeted by Batfish, curiously circling around us, while Barracudas held their ground against the current.

Later, at Koh Tachai Pinnacle, we navigated through massive boulders draped in soft coral, discovering Lobsters tucked away in crevices, more Barracudas patrolling the reef, and a sleek Black Tip Reef Shark gliding effortlessly past—an exhilarating finale to an unforgettable dive.

Our final two days at Richelieu Rock were nothing short of spectacular. The site was teeming with life–Ornate Ghost Pipefish hovered gracefully among feather stars, Tigertail Seahorses clung to delicate sea whips, and Porcelain Crabs filtered plankton with meticulous precision. Banded Stick Pipefish wove through the reef, while Big Eye Trevallies and Giant Trevallies darted back and forth in a relentless hunting frenzy.

In the blue, schools of Barracudas hung motionless, suspended in perfect formation. We were mesmerized by a vast mixed school of Rainbow Runners, Emperors, and Big Eye Trevallies, moving in unison like a single, fluid entity. Red Snappers lurked near the coral formations, adding the final flourish to an already unforgettable experience.

As we sailed back to Ranong, the excitement and memories of the trip lingered among our group. The Whale Shark Expedition had given us not only breathtaking encounters with Thailand’s marine giants but also a deeper appreciation for the intricate beauty of the Andaman Sea’s underwater world.

Until next time, we carry with us the wonders of the deep and the hope for future encounters with the gentle giants we strive to protect.