Similan Islands

Some time ago, I went on my first diving safari to the Similan Islands. It's time to tell you how it went.
What is a Diving Safari?
A diving safari is a sea adventure on a comfortable boat with an intensive diving program that fully reveals the underwater world of a specific area. The vessel used for a diving safari is equipped with all necessary diving gear. The boat crew always includes several dive guides who know the diving conditions and the most fascinating dive spots well.
During a safari, there's a unique opportunity to dive in places that are difficult to reach in a single day.
About the Similan Islands
The Similan Islands are an archipelago in the Andaman Sea, located west of the southern coast of Thailand. The Similan Islands are ranked among the top 10 diving destinations in the world. Excellent visibility, abundance of marine life, reefs, deep sites up to 30m and more. Everything needed for good diving. You can only sign up for a dive safari with an Advanced certification or higher.
The archipelago is a national marine park of Thailand. This ensures its protection and conservation of natural resources, as well as control over tourist activities for sustainable use of nature. The islands are open for visits 6 months a year, from mid-October to mid-May (Correction: original text said March, but May is the usual closing month).
The name "Similan Islands" comes from the Malay language and means "nine islands." The archipelago includes nine main islands, as well as several smaller ones. Their Malay names are "Koh" (meaning "island") and numbers from one to ten, except for the seventh, which is considered unlucky in Malay tradition and is therefore skipped. Thus, the Similan Islands include Koh No. 1, Koh No. 2, and so on, up to Koh No. 9.
First Dive: Three Trees
The first dive was at the Three Trees dive site, located off the ninth island. It features a sloping reef descending to a flat sandy bottom. On the sand, there are several rocks and coral reefs with beautiful gorgonian fans and soft corals. On these rocks, you can see rays, barracudas, trevallies, and sometimes sharks, while turtles inhabit the reef.
As the divemaster said, the first dive is a check-out dive. "You might have 1009 dives, but we will watch how everyone swims, and you must show us what you can do." When I heard this, I thought, "What heresy." But then I understood what he meant.
We dived as a group of three for the first dive: the local divemaster and a guy from Germany (Frank), who said he had 500+ dives. But what he didn't mention immediately was that his last dive was a year ago, and the gear wasn't his but rented. As a result, he struggled to descend. He had poor buoyancy control and breathed a lot. We dived for 40 minutes, but the divemaster was a bit nervous because of the German, and towards the end, Frank had to breathe from the divemaster's octopus. Despite all this, it was cool, and the underwater world started to amaze from the first dive in a new place.
Second Dive: North Point
The second dive was also off the ninth island, but at the North Point dive site.
North Point (also known as Rocky Point), located northeast of Similan Island 9, is a dive site consisting of underwater rocks mixed with a shore reef as you approach the island itself, making it an excellent spot for divers of all levels. The rock formations create holes and passages. At depth, there is a small pinnacle where, if lucky, you might see sharks swimming in the sandy channel. The deep rocks are covered with giant sea fans.
In the southern part, near the island, there are two channels formed by boulders standing side by side. Near the channels is a shallow fringing reef composed of staghorn and hard corals.
This time we were regrouped, and I went with another group that breathed less and theoretically should swim at the same level.
And so it happened, but there was a nuance. On the second dive, visibility was poor. Very murky water and strong current. Plus constant thermoclines. The water temperature momentarily dropped below 25 degrees Celsius!! Brrr. Strong current + cold water. As a result, air was consumed incredibly quickly. About twenty minutes in, when I had 120 bar left, I realized something was wrong with my weights. I started feeling a strong pull upwards. Of course, the water currents between the rocks played their part, but feeling my pockets, I realized I hadn't put in one weight. Not critical, but I had to exert myself.
Despite having to fight the current, everyone breathed consistently. And a lot =) But we managed 45 minutes. Didn't see much, but gained experience in current. It has its own charm, but it's physically demanding.
After the dive, we settled into the cabins. Small twin shares. But at least they have windows)
Very lucky that I went at the beginning of the season; the boat was half full. There's also a lower deck, below the waterline, and those cabins can only be occupied with artificial light and air conditioning. Not comfortable. So it wasn't too bad being roomed with Frank; anyway, you only sleep in the cabins, and the rest of the time between dives can be spent in various relaxation areas on the boat.
Third Dive: Koh Bon
The third dive was at Koh Bon island, located north of the Similan Islands, though still considered part of the Similan National Marine Park. The favorite dive spot is the western ridge of the islet, which drops steeply into the depths.
The reef slopes down from 10m to a sandy bottom at 25-30m. Most corals here are hard corals, including staghorn and brain coral. The ridge is covered with tiny yellow soft corals and teems with life due to the usually moderate/strong currents, but this is precisely what attracts large fish here. This is the number 1 spot in Thailand to see manta rays (but not this time).
After this dive, I began to understand why the Similans are ranked among the most beautiful diving spots.
At the beginning of the dive, the site resembled something between Phi Phi and Racha Noi. Sandy bottom sloping into the depths and blue water. It was cool, especially because there was no current, and you could catch the feeling of flying.
And then we reached the corner of the island, and it began... We were met by a thermocline with cold water and a strong current. I remembered the fatigue from the previous dive again, and even thought, "what, again?!". But two minutes later, we rounded the corner, and a gentle warm current picked us up, and I saw them. A school of huge barracudas and slightly less huge trevallies! There were an incredible number of them.
And all this mixed with small fish that unabashedly swarmed towards me. And above and below, these giants. We drifted with them in the current, and it was exhilarating. Blue water to the left from which hundreds of fish appeared, a wall to the right covered in untouched corals, and blue water. Bliss.
Incredibly beautiful dive site. And they say it's not even the best one. Surfaced almost at sunset, full of delight and with a feeling of slight fatigue.
And the next dive is a night dive. At 7:00 PM :) Technically the sun will have set, so yes, a night dive )
Dive Four: Koh Tachai Reef
Koh Tachai island is located beyond Koh Bon. Koh Tachai island has two dive spots: the reef and the pinnacle.
Koh Tachai Pinnacle is a huge granite plateau covered with soft corals, sea fans, and anemones. Strong currents bring food from the depths and attract large schools of fish: trevallies, mackerel, tuna, sharks, and sometimes manta rays and whale sharks.
The Reef consists of coral blocks lying on the sand. Maximum depth is 20 meters. This place is inhabited by reef sharks, spotted rays, and sea turtles. The reef itself is populated by all kinds of reef fish, including parrotfish, redtooth triggerfish, snappers, and wrasses.
This was my first night dive ever. And again, I was completely thrilled. Firstly, before the dive, I watched the sunset, pleased that everything looked like a good movie, and I was the main actor. And then, gear up, turn on the flashlights, and into the water.
The feeling of outer space. Dark everywhere, and only the beams of flashlights snatch underwater inhabitants out of the void, appearing from nowhere and disappearing just as quickly. Fish, corals, barracudas, and even a turtle! She was certainly surprised to be disturbed here, but we were careful and didn't linger.
This was the shortest dive of the entire safari; we agreed to swim for 30 minutes and surface, but in terms of impressions, it definitely ranks in the top three. After all, it was my first dive and new sensations.
We surfaced at a distance from the boat. A rubber dinghy was supposed to pick us up. I thought it would be as usual, throw a rope and start towing us. But no, this time he lowered a ladder, and we had to climb onto it. This caused some difficulties, especially when picking up another group. When another diver climbed up not quite successfully, the boat started rocking so much it seemed like it would capsize. But everything turned out fine.
After everyone was seated, they asked us to turn off our flashlights, and we sailed in complete darkness towards the main boat. Impressive. Boarding the ship felt like pirates)
Afterwards, there was dinner, and we went to our cabins to sleep. And the ship sailed for another 4 hours to the next diving spot, Richelieu Rock.
Fifth Dive: Dawn at Richelieu Rock
Woke up in the middle of nowhere. Islands visible on the horizon. But we stopped in the open sea. Today we dive three times at the most beautiful dive site, Richelieu Rock.
Richelieu Rock is an isolated, horseshoe-shaped pinnacle located near Koh Tachai island and geographically belonging to the Surin Islands. Only the top of the rock is visible at the sea surface, not exceeding 1m during low tide; during high tide, Richelieu Rock is completely submerged.
On a clear day, visibility can reach 35 meters, while on other days, it might be no more than 10-15 meters. Reduced visibility is usually due to large amounts of plankton, which is the main reason for periodic visits by whale sharks.
Richelieu Rock is ranked among the top ten dive sites in the world by most diving magazines and is undoubtedly the best dive site in Thailand.
The first dive was before breakfast; we went underwater at 6:50 AM. Unlike us, the fish had already started their meal, and it was amazing. The abundance of fish at this site is mesmerizing. On morning dives, Richelieu Rock resembles a large dining hall. A diverse quantity of fish of all colors and sizes hunt each other, paying no attention to the divers.
Thousands of diverse fish of all colors and sizes. Simply an incredible place to dive.
Sixth Dive: Richelieu Rock
The completely untouched reefs of Richelieu Rock host an enormous amount of marine life. Several species of ever-hungry barracudas and trevallies patrol the area, hunting among the vast numbers of reef fish. Their main prey are large schools of snappers and fusiliers feeding in mid-water. The rock itself serves as shelter for hundreds of different species. Lionfish, mantis shrimp, lobsters, octopuses, trumpetfish, colorful nudibranchs, mating cuttlefish, and giant groupers are just some of them. Among the beautiful gorgonians and huge gardens of soft corals, even ghost pipefish live, and the yellow tiger-tail seahorse is always hard to find. Additionally, the cracks and crevices in the limestone rocks provide excellent hiding places for moray eels and scorpionfish. - from large pelagic fish, predators, schooling fish, and others, down to macro life such as seahorses, ghost pipefish, nudibranchs, and many more, including whale sharks on a lucky dive day. Growing up to 16 meters long, whale sharks are the largest fish on the planet, and their lifespan is believed to exceed 100 years. Didn't get to see one this time. But I will definitely return here again, and maybe next time…
After breakfast and a rest, we dived Richelieu Rock again. Two hours after the morning dive, the sun began to penetrate the depths, and underwater life sparkled with new colors. The corals here are similar to what I'm used to, yet slightly different. Also, this time I paid more attention to the smaller inhabitants. Tracked down little crabs hiding in the corals along with clownfish.
Caught myself thinking more than once that it was good I didn't go last year when I wasn't so confident underwater. I clearly would have missed a lot. Now I can calmly control several things simultaneously, enjoy the views, and think about what to write in my notes)
Seventh Dive: Last Dive at Richelieu Rock
There are many different stories and myths about the origin of this dive site's name. One claims the name was given by Jacques Cousteau himself, as the shape and colors of the rock reminded him of the famous Cardinal Richelieu's cloak from "The Three Musketeers" (the outside of the rock is covered in purple soft corals).
According to another version, held by our captain, the rock was named after Admiral Richelieu, commander of the Royal Thai Navy, confirmed by the existence of official Navy charts mentioning Richelieu Rock dating back to the early 1900s. Richelieu was the first person to conduct a hydrographic survey of the Andaman Sea, including the area in question.
The last dive at Richelieu Rock, we agreed to stay no deeper than 20 meters. But 5 minutes after starting the dive, I noticed a large octopus on the bottom. Quickly exchanging gestures with the divemaster, I began descending towards the octopus to film it. Over half a meter in size. Beautiful, but intimidating. It tried to hide in the corals at a depth of 27 meters. We slightly broke the agreement, but at the debriefing, we both agreed it was okay, as we spent maybe a minute at that depth, and the rest of the dive was, as agreed, at 18-20 meters.
Richelieu Rock is indeed a very beautiful and captivating dive site. It's a pity we didn't see mantas or sharks, but there were still many beautiful and new creatures for me. Definitely want to return here. But perhaps during the spring season. Giants are most often seen here around the end of February.
Eighth Dive: Koh Tachai Pinnacle
Koh Tachai Pinnacle is a submerged group of giant granite boulders where very specific (often strong) currents prevail, attracting an incredible amount of predatory fish that gather in schools. The summit is at about 10m depth and is equipped with a mooring line/buoy to assist divers during descent. There are actually two pinnacles here, the main southern one being larger, and where most dives on Koh Tachai Pinnacle occur. It's a huge dome-shaped boulder surrounded by many smaller ones. The scenery at the pinnacle is very diverse: on the south side, there are large, oddly shaped boulders creating a stunning underwater landscape, while the north side features one of the most beautiful and untouched coral gardens in Thailand. This huge pinnacle connects to the smaller northern pinnacle via a sandy patch at 24m, a swim of about 50m. The top of the northern pinnacle is at 18m, includes a wide range of rock formations, and is home to large, beautiful sea fans and pristine soft corals. But the amazing underwater terrain and coral reef pale in comparison to the insane amount of fish and marine life found at Koh Tachai Pinnacle. Large schools of huge giant trevallies, bluefin trevallies, dogtooth tuna, and rainbow runners often hunt around the boulders, presenting a breathtaking spectacle. Occasionally, huge schools of chevron barracudas can be encountered over the pinnacles.
The last dive for today was at a new spot. We dived the reef here at night, and now we came to the main dive site. At the briefing, they said the current could be very strong, but we were lucky and only encountered current towards the end.
Swam a lot in the blue among schools of large barracudas and huge tunas. Huge means about one and a half meters long and half a meter wide.
Cool to watch them hunt smaller fish. Another cool sight was fish swimming in pairs: silver and black (Trevallies). Unusual, but couldn't capture it on video/photo. There were also cartoonish starfish and large lobsters )
Overall, a pleasant day, dived well. After the dive, went to watch the sunset while the boat sailed to the next dive spot.
Ninth Dive: Shark Fin Reef
The Shark Fin Reef dive site is a very long line of huge granite boulders stretching south and east from Similan Island No. 3 (Koh Payan). This is the closest point to the marine sanctuary at islands 1 and 2 (Koh Huyong and Koh Payang). In the middle part of Shark Fin Reef, the boulders break the surface as peaks resembling a shark fin, which gave the dive site its name. On the south side, the pinnacle features a steep slope meeting the sand at about 25 meters. Along the slope are several large boulders where moray eels, lionfish, and scorpionfish hide, while blue-spotted stingrays are often found on the sandy patches, and on a lucky dive, leopard sharks too. To the northwest is a flat plateau with several rocks and pretty coral bommies. This part of the dive site attracts the most fish as it's more exposed to the current.
Another morning dive. It was quite dark underwater, and this, as usual, was mesmerizing. I think this is how the world might look after a global catastrophe. Desolate, gloomy, and calm.
Unfortunately, didn't find a shark, but watched Sean manage schools of fish with his SMB. Cool magic. I'll adopt that technique.
During the dive, I felt a bit melancholic. Maybe tired, but more likely because it's all ending today, and I'll have to return to land.
Tenth Dive: Stonehenge Pinnacle
The dive site known as Stonehenge in the Similan Islands got its name for obvious reasons. It's a deep dive in the center of the Similans, consisting of a group of huge granite boulders resting on a sandy bottom. It's located off the northwest tip of Koh Miang (Island 4) and isn't very suitable for inexperienced divers or those with high air consumption.
The challenges at Stonehenge are the moderate to strong currents and the minimum dive depth of 24m. For experienced divers who enjoy deep dives, exploring passages, canyons, and caves, and can handle the current, it's a wonderful dive site right in the heart of the Similan archipelago.
Due to its depth, difficulty, and lack of snorkeling opportunities, Stonehenge is generally visited less often than many other Similan dive sites. Therefore, you can have a lot of fun and see many interesting things here.
The dive turned out mixed. We descended in good visibility, but then went deeper searching for something large. But the problem arose that there was a cold current full of silt there. So we ended up swimming in even more gloom than the previous dive. After about ten minutes, decided that luck wasn't with us and moved to a shallower area. And here the name justified itself. Lots of large boulders that looked like something unnatural and forgotten. And large schools of fish among them. A pleasant feeling of flight and a thought in my head: "Cool that you can move in any direction. That's why I love diving."
Eleventh Dive: Tsunami Monument (Hideaway Bay).
The 2004 tsunami had a truly devastating impact on the town of Khao Lak in Thailand, the main departure point for diving safaris to the Similan Islands. At the Hideaway Bay dive site in the Similans, a permanent underwater memorial depicting the 12 signs of the Chinese Zodiac was installed.
The last dive turned out to be private. Went just with Sean; the guys who dived with us before had a flight within 24 hours, so they decided to skip the last dive to reduce the risk of DCS.
The dive was simple, and we spent most of it no deeper than 10 meters. A nice, pleasant dive in clear water, sandy bottom, and sun rays. Looked at the monuments placed underwater after the 2004 tsunami.
But the main impression came at the very end. As we were surfacing, we encountered a huge turtle near the boat. As one instructor used to say, "If you see a turtle, you have good karma." A cinematic moment. And a sign to return again )
The End
After the last dive, we packed our things, boarded a speedboat, and headed back to the mainland. It was funny observing people on the way back. When we were just heading to the boat, everyone was tense and focused. I was the same. On the return trip, everyone was in a good mood. Lots of smiling and talking.
It was an excellent adventure that I will definitely repeat someday.