Remote and wonderful in the Andaman Sea
The Kingdom of Thailand, a sprawling Southeast Asian country slightly larger than California, shares land borders with four countries and neighbors a fifth by sea. It is a progressive sovereign nation that remains deeply rooted in culture and customs. With the ninth-largest economy in Asia, it is also one of the most popular tourist destinations.
Thailand is naturally picturesque, featuring spectacular granite and limestone rock formations that are popular for rock climbing and caving. The highlands of the interior and neighboring countries serve as foothills to the Himalayas far to the north, formed by the colliding, uplifting, and folding of tectonic plates. Dense jungles and fertile valleys comprise the north’s interior, with lakes and rivers leading to the white sand beaches further south in the Gulf of Thailand and the Andaman Sea.
Thailand boasts more than 2,000 miles (3,219 kilometers) of coastline, much of which is highly scenic. Continuing south, Thailand shares the narrow Malay Peninsula with Myanmar and Malaysia, effectively separating the Gulf of Thailand from the Andaman Sea.
I was surprised to learn that there are more than 150 national parks in Thailand and 60 wildlife sanctuaries designed to protect and preserve its unique forests and wildlife. With some of the parks established more than 60 years ago, it’s clear that the Thai people have an affinity for wildlife and open spaces. The parks include locations not only on land but also in the sea, encompassing clusters of islands and forming several marine sanctuaries, including our destination — the Surin Islands in Mu Ko Surin National Park.
Our adventure began in the rural port town of Ranong, a peaceful escape just an hour’s flight from Bangkok or a five-hour drive from the bustling city of Phuket. In the coming days we planned to weave our way through the many smaller islands and dive sites to our final destination, the iconic Richelieu Rock.
Mu Ko Surin National Park, a strictly monitored park system open from November through mid-May each year, attracts thousands of divers annually. Park rangers monitor dive boats and commercial fishing, poaching, and other activities to ensure marine life, corals, and terrestrial animals are well protected. The islands are remote, but Richelieu Rock is one of the world’s top dive destinations, so you may encounter other groups of divers while visiting.
On our first day we explored pinnacles, cleaning stations, macro sites, and healthy coral reefs around Koh Chi dan Torinla Pinnacle. The moderate current carried us along gentle slopes, where coral gardens garnished with glassfish quickly grabbed our attention. We were treated to various reef fish, such as common parrotfish and spotted coral groupers, rainbow runners, mackerels, and batfish.
Nudibranchs, blennies, and gobies were abundant at Torinla, making for a great macro dive. Large granite boulders appear to have been dropped from the sky to form a single pile with a few stragglers in the sand. It seems barren here at first glance. Once you approach the boulders you begin to see the activity between them, and macro critters are abundant where the sand meets the reef. Once we discovered this, we hardly moved from our position, as there were enough critters to keep us clicking until the end of our bottom time approached.
Yellow Rock and its pinnacles awaited our arrival in the afternoon, and this is where we would rest for the evening. An armada of great barracudas awaits to greet divers as they slip below the waterline. Large granite blocks on the seafloor form several mounts, small valleys, and mini walls that shelter various marine life.
Large sea fans tell a story of an area subject to heavy currents, although it remained gentle enough during the peak tide on our visit for a relaxing and colorful afternoon dive. Soft corals coat many of the granite slabs, making them pop with a soft yellow hue, giving the site its name. Fish were flying, cleaning stations were in full swing, and the pinnacles were vibrant and vivid. We played hide-and-seek with large potato groupers, discovered spiny lobsters below ledges, and watched mangrove snappers casually move about. This was the only location where we encountered other divers aside from Richelieu Rock.
In the following days we visited Koh Tachai dan Koh Bon cleaning stations, where hordes of batfish lined up for their daily spa treatments. Divers can also see leopard sharks at Koh Bon, where a drop down to the sandy slope is necessary for a chance to encounter these beautiful and docile sharks.
Blackwater diving in Thailand isn’t easy from shore due to the seabed’s shallow pan, but the depths near Koh Bon were perfect for the opportunity. After dinner Capt. Franck gave us a safety briefing, and his crew put us into position, using the mother ship as our platform.
One subject I was seeking during this trip was a yellow-bellied sea snake, which is in the cobra family and averages around 3 feet (1 meter) long. Unlike others in shallow coastal regions, this sea snake lives in the open ocean. The dive deck was buzzing with anticipation as we dropped our lighted downline and hit the water. The search was on.
I have always been fascinated by reef structures, particularly their location-based variations. The Indo-Pacific primarily originates from volcanic activity, resulting in formations made of compressed cooling magma, igneous rock, and eventually darker sands. Conversely, the reefs in Thailand differ from those in the Indo-Pacific; they are shaped by the collision of major and minor tectonic plates and rising intrusive granite that can be traced to the Himalayas. Geometrically shaped granite blocks and boulders created millions of years ago are now teeming with marine life and coral beds. Thailand is not a part of the formal Ring of Fire, and proof of that is evident in the bedrock.
Fish generally gather wherever there is structure. The Andaman Sea’s relatively shallow water and flat pan lead to a significant congregation of marine life around its structures. The abundance of fish in these locations is surprisingly refreshing and speaks to the conservation efforts being made here.
Up to this point of the trip our group’s energy and anticipation had grown steadily, but nothing prepared us for what we were about to encounter at our next location, assuming the weather held.
Approximately 28 miles (45 km) from the mainland is Richelieu Rock (Hin Plo Naamin Thai),a horseshoe-shaped dive site with wash rocks that break the surface. From October to March, Richelieu is completely exposed to the elements and rapidly shifting conditions, and there are no other islands or structures for many miles around.
We awoke to the prediction of strong winds and possible rain, meaning there was a small craft advisory. The smaller day boats from the mainland couldn’t leave their harbors, but our liveaboard wasn’t small, so we set out from our safe harbor with caution. Mother Nature stirred up a tempest that nearly prompted us to reverse direction, but the storm was moving fast and bypassed us for the most part.
We were alone on Richelieu Rock for more than two days, allowing us to explore and experience Richelieu in all its glory. It was the fishiest dive site I’ve ever dived, exceeding all my expectations. The sheer energy and movement of the mass of fish gathering and hunting were distinctly audible. Until Richelieu, most of the reefs we visited had their smatterings of glassfish, but here they enveloped the entire structure, creating feeding frenzies among the resident predatory fish.
Our first dive was an early morning jump that began near the wash rock, and the reef looked fuzzy as we descended. I don’t know how to describe what I first saw, but the structure was moving. I quickly realized that I was looking at so many glassfish that they prevented us from seeing the details of the reef below.
The water was dark and thick with plankton, and the current was moderately heavy. Marauding emperor fish and powerful giant trevallies rule the rock and hunt in dense packs by cutting away the glassfish from their schools. These hunters take no prisoners and keep the entire rock buzzing with sustained nervous vigor evident among all the smaller fish. The activity was initially overwhelming as the rhythm seemed so random and eruptive. I couldn’t wait to get back in the water after each surface interval, each of which seemed to pass more slowly than the last.
It takes a few dives to absorb the beauty of Richelieu Rock, so I was happy that our itinerary included two and a half days to experience it, and being the only liveaboard there was the cherry on top.
The outer portions of the reef system slope down sharply to the sand at about 100 to 120 feet (30 to 37 m), where the seabed flattens. Limestone rocks are pushed up and piled on one another, forming a loose horseshoe shape with several other pinnacles. The interior rises between the pinnacles and forms a valley that provides a current-free sanctuary filled with snappers, batfish, coronet fish, barracudas, and many more. It is like being in an aquarium, with a relaxed rhythm contrasting heavily with the never-ending hunting activities along the outer reef.
The rocks form a colorful reef network with purple soft corals and carpets of anemones, sea fans, gorgonians, and several types of sponges. The macro opportunities are also quite good, with frequent sightings of ghost pipefish, harlequin shrimp, and various nudibranchs. I couldn’t bring myself to shoot macro with all the activity going on, however, and I spent every second with my head on a swivel watching for pelagic animals.
The northern pinnacle was the most active, so I spent most of my time there. From a position near the top of the reef I could watch and listen as massive schools of trevallies worked the schools of snappers and glassfish with what seemed like well-orchestrated teamwork. They would masterfully redirect the schools of smaller fish back and forth with an increasing tempo, making sharper and faster turns until a small group of fish finally missed the turn, and the ravenous trevallies would quickly devour them. The entire rock would explode with activity every half hour or so, followed quickly by silence and a subdued lull. This cycle went on all day until late into the afternoon.
Because of Richelieu Rock’s isolated location, you never know what will happen. It always pays to keep an eye on the open water when diving here, as the mass of marine life attracts many visitors. On our final morning of diving, our team was the first in the water, and as we descended along the outer reef walls, I glanced up to see a giant shadow overhead and the unmistakable outline of a whale shark as it passed through a dense cloud of baitfish. While I was engrossed in shooting photos of it, I missed two large mantas that passed by. This bonus rounded out our days on Richelieu Rock and left me with many gigabytes of images to review.
As we motored back toward our port in Ranong and neared the end of our journey, we shared our images and swapped stories from the trip. Even though we all had different experiences, we agreed on the success of the Mu Ko Surin National Park. The Surin Islands are one of Thailand’s most precious locations to dive, and they have significantly improved since becoming part of a national park.
Thailand will dazzle your senses, pique your spirit, and leave you wanting to come back and explore this humbly beautiful part of the world.
Cara Menyelam
Sampai di sana: Fly into Suvarnabhumi Airport, one of Bangkok’s two international airports, and be sure your connecting flight to Ranong leaves from there, or fly directly to Phuket. Taxis and Grab (Asia’s ride-hailing service) are readily available. Expect traffic wherever you go, so allow extra time. Visas are granted to visitors from most countries upon arrival, but travelers can apply for an e-Visa ahead of time.
Thailand has one foot in the modern world and another foot firmly secured in tradition. The national language is Thai, with different dialects throughout the country. Most people speak English to some degree, and getting around is both safe and simple. The official currency is the Thai baht. The Mu Ko Surin National Park entrance fee is 500 baht ($15US) per day.
Dive planning: Mu Ko Surin National Park is in a remote part of the Andaman Sea and requires a multiday liveaboard. Depending on the itinerary, boats depart from various ports and often don’t return to the port of origin. Plan for seven to 10 days of diving with a few extra days to enjoy Bangkok or Phuket. The liveaboards in this area sell out at least a year in advance, so plan ahead and schedule at least eight dives on Richelieu.
Kondisi: The water is warm all year with variable visibility, depending on the month. Expect inclement weather from November through January with compromised visibility. Visibility is exceptional from February through the high season of April and May. The park is closed during the rainy season from mid-May through October.
Jelajahi Lebih Lanjut
See more of what Thailand’s Surin Islands offers in a bonus photo gallery and this video.
© Penyelam Siaga – Q2 2025