by Jill Studholme, 7 July 2023
The best diving in Thailand is in the Andaman Sea, to the west of the kingdom. Two dive sites you shouldn't miss are in the Southwest: Hin Daeng (Red Rock) and Hin Muang (Purple Rock). These world-class diving sites deserve to be in every divers' top 10. Other places to target are the Similan and Surin Islands.
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From October to April is the best time for the Andaman Sea. Giant Manta Rays arrive at the Similans in March and April. At Richelieu Rock you might also be lucky enough to see whale sharks during this time. Come May though, heavy rainfall hits the West coast of Thailand and continues until September - the marine reserves which host most of the best diving are closed from May to the middle of October. During this time of year, the Gulf of Thailand to the east of the country is a better option. The best diving on this side is around Koh Tao, although it can be very crowded.
Thailand has very clear waters and an average water temperature of 28oC. The Thai people are friendly and welcoming, and the food is fantastic. They tend to serve very mild food to their western guests: if you like hot food then tell them. But be careful, even the most hardened European chilli-eater has been seen to sweat with home-made Thai-strength curries.
The Thai authorities try to protect their coral reefs, closing dive sites if necessary. The government operates strict controls in the Marine National Parks. For instance, all boats must be maintained to a high standard, no rubbish is to be thrown overboard and the feeding of fish and other marine creatures is forbidden. The maximum depth for dives in the marine parks is 40 m and no-one may do more than three dives as day.1 There are 27 marine parks in Thailand, 17 in the Andaman sea and 10 in the Gulf of Thailand.
Thailand has something for everyone, no matter what your diving experience. With over 2000 km of coastline, and hundreds of islands, there are reefs, walls, caves, drifts, swim-throughs, drop-offs, wrecks and pinnacles.
Hin Muang Hin Daeng Koh Kradan Wreck Hin Nok Ko Ma Koh Rok Nai Koh Rok Nok Shark Point or Hin Bida Ko Bida Nok Koh Phi Phi Koh Dok Mai Koh Waeo Racha Yai Kata Beach King Cruiser Wreck Tin Lizzy Wreck
Hin Muang and Hin Daeng are feeding grounds for pelagic fish. They are fantastic dives, and worth the trip to Thailand. Hin Muang features large underwater pinnacles heading southwest. You'll be entranced by huge shoals of fish, beautiful anemone carpets, soft corals and gorgonions. Look out for the unusual bryazoan - clumps of white, straw-like things at around 8 metres. Sharks, tuna, enormous barracuda often visit and the deepest drop-off in Thailand is here. Don't go home without visiting Hin Muang or you'll have missed the best diving that Thailand has to offer.
"Hin Daeng and Hin Muang are deep dives with amazing color in the coral formations and anemones. Also a popular spot for whale sharks."
"Lots of fish at this site, both large and small and some beautiful red soft corals. Great dive."
Peter, UK, 2013
Hin Daeng is close to Hin Muang and comprises walls, plateaus and rocks. You will might see leopard sharks, grey reef sharks, morays, barracuda, octopus, crayfish, shrimps. Nurse sharks are sometimes found in the south west cave (around 10 m) and whale sharks and manta rays also visit. The dive is fantastic not just for the big stuff you might see, but for its beautiful soft corals. Another unmissable, world-class dive site
"Again, lots of fish and this time, purple corals."
Peter, UK, 2013
Said to be a Japanese destroyer, this wreck is off the coast of Koh Kradan Island. Many fishing nets drape over the stern of the wreck. The visibility is often poor below the thermocline at around 15-20 m. It is difficult to make out detail of the wreck, but look at the life instead as you may see a seahorse! Check the ropes carefully for Hippocampus kuda. Also many soft corals, schooling fish, lionfish and giant morays.
Hin Nok comprises a plateau with five pinnacles and lots of gullies It is north west of the Koh Kradan Wreck. You can swim right around the plateau in about an hour. A very interesting dive. Hin Nok is visited by turtles and is home to the very unusual Ghost Pipefish (Solenostomus paradoxus). This feathery fish is difficult to spot. Not only does it not look anything like a fish, to further confuse you it sometimes floats upside down in the water. Also look out for nudibranchs like Jorunna funebris, moray eels, whip corals, barracuda, moorish idols, butterfly and angel fish.
A shallow dive, nothing spectacular but several unusual fish to be seen. Look for the shrimpfish, Aeoliscus strigatus, which is long and thin and hangs vertically in the water the tail up. It propels itself with tiny, fan-shaped fins. A fascinating fish, generally in pairs or larger groups.
This dive features large gorgonions, nudibranchs, moray eels and a tremendous amount of small fish in the rocks. At first glance these fish look like anemones, they are so tightly packed together.
You'll see loads of 2 m leopard sharks here. Look out also for cuttle fish and seahorses. A series of rocky fingers project south of an outcrop - the gullies in between the fingers protecting you from the current.
A rocky outcrop featuring varied diving: walls, shallow reefs, boulders and swim-throughs. Look for leopard sharks on sand, cuttle fish, massive tube corals, gorgonians and lots of colours.
To visit Koh Phi Phi you need to pay a 400 baht national park fee plus 200 baht diving fee. However, if you arrive at Ton Sai Pier on Phi Phi Don you are not subject to the national park fee. Phi Phi currently has 18 dive spots "open" in the national park.
"I just got back from Thailand where I took the Open Water course on Ko Phi Phi (12700 bhat - just under 400 USD). I then travelled to the Khao Lak to dive at Richelieu rock, finishing the trip in Ko Tao. Learning to dive in Ko Phi Phi was great. Even snorkelling off Long Beach meant seeing black-tip reef sharks every time. The visibility was good, the variety of sea creatures was great (leopard sharks, sea turtles, sea snakes etc) and it wasn't overcrowded. "
Simon Dragland, 2008
Photo by Jurgen Hertoghe on Koh Dok Mai
"I actually preferred the beach dive at Kata. Racha Yai was great vis. but there's not much coral there and it's a bit lunar. Still there are some interesting fish to see, and there's a couple of small wrecks and an old moped to play around with! "
Kay Turner, UK, 2016
"Coral gardens, boulders. Overall good easy dive"
"The visibility wasn't great but we saw the most incredible amount of different fish. There's a colony of I don't know how many stingrays. Rachel (of Oceanic Dive Center) wouldn't promise that we'd see them but she found them. There we so many fish at the artificial reef I didn't want to leave! It was a real surprise but everything Rachel had said we would see, we saw, and more!
Kay Turner, UK, 2016
In 1997 the King Cruiser, a 3000 ton catamaran passenger ferry, hit Anemone Reef. Within an hour the ship sank with no loss of life. It rests in an upright position with the steering house 10 metres from the surface and the propellers at 30 metres.
"Currents, not good vis. normally I'd be unhappy about things like that, but it just doesn't matter at this wreck dive. There are so many fish schooling around the wreck you won't know where to look. And it's covered in lovely soft corals, nudibranchs everywhere! Lovely. I can't wait to go back there.
Kay Turner, UK, 2016
"A very beautiful dive with great shoals of colourful fish on the wreck."
Dean Evans, UK, August 2012
"Current is pretty strong, beginners could freak out, visibility was not great but good enough. Lots of urchins, so maintaining buoyancy was important."
"Wreck dive in Phuket off west coast. Better than King cruiser because visibility more clear"
Suriyan Soison, Bang Tao Scuba, 2013
My first view of the Similans was similar to seeing the Grand Canyon for the first time. For lack of a better word: awesome. Tranquil white sand beaches and turquoise water with gin clear, 60 m visibility. Meadows of soft corals and sea fans combined with a prolific fish population are the main reasons this is a world class dive destination. Pelagics in this region are seasonal. Though there have been plenty of sightings of Mantas and whale sharks, they are not common. The best chance of seeing them is during the plankton bloom in March and April. For the non SCUBA Diver, snorkelling the Similans is second to none. In fact, because of the drift currents on many of the islands, you can often see more variety of marine life in the protected shallow areas. (Bill Mashek)
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An archipelago of nine uninhabited islands, the Similans are around 90 km northwest of Phuket. There is quite a difference between the west and east sides of the islands. The east coasts are sheltered and have gently sloping reefs, coral gardens and large shoals of fish. The west coasts are hit by storms between May and September and underwater you see archways and swim-throughs. The currents bring nutrients for gorgonians, beautiful soft corals and feather stars.
Each island has a Thai name, but they are also numbered 1 to 9 from south to north.
|Similans Island Number||Similans Island Name|
|7||Ko Hin Pousar|
The best time to visit the Similans is from November to April. Indeed, much of the Similans is closed to divers outside this time. Manta Rays visit from February to April. For dive boats visiting the Similans see our Thailand Dive Operators page or see liveaboard deals here.
A Similan classic: turquoise water, fantastic visibility and copious fish population. Look out for the banded sea-snakes, extremely poisonous but not aggressive. Stay calm if you see one and enjoy the experience. The dive is called Breakfast Bend as it is often the first dive of the trip, done immediately after breakfast. A very good dive with leopard sharks, powder blue surgeon fish, scorpion fish, barracuda, morays, emperor angelfish, trigger fish and shoals of glass fish.
Pre-eminent coral formations. Lots of small fish: rabbitfish, clownfish, lionfish, garden eels, boxfish and others. Excellent visibility.
"Fantastic drift dive. Huge variety of corals and marine life."
Gordon Ollivere, UK, September 2015
Giant boulders, sitting alone or piled up to make arches and tunnels. Currents can be strong. Lots of soft corals, hard corals and sea fans.
"3 rocks stick out at the surface, depth subject to training level, swimthroughs, excellent huge boulders, some holes to look through, excellent dive!"
A fast drift dive on one side of the island, slackening off as you turn the corner. A good place for lobsters, ribbon eels, garden eels, hunting trevally, glass fish, morays and trigger fish.
The dive slopes down past large granite boulders. At 27 m there is a swim-through with a large sea-fan. Look out for the garden eels at 23 m.
You'll see blue-spotted stingrays, garden eels, bumphead parrot fish, moorish idols and schools of glassfish. Likelihood of vigorous currents. One side comprises a drop-off, the other a sloping reef. A swim-through at 16 m takes you from one side to the other.
A wall descends to a sandy patch covered with blue spotted stingrays. On to an eel garden then up among boulders. Look for leopard sharks and guitar fish.
A large (3 m) bow-mouthed guitar shark sometimes lurks here. There can be a strong current which means lots of fish including big trevally and glassfish schools.
Koh Tachai island is the most northernly part of the Similans marine national park but outside the main nine islands that make up the Similans archipelago. At the moment the island is closed to tourists. You can still dive in the area though.
"Huge schools of barracuda's, tuna and trevallies, leopard and white tip reef sharks! Been several times to the Red Sea but Similan, Surin and Koh Tachai beat everything!
"12m to the top of the pinnacle. Can be fierce currents, recommended for advanced divers. Action dive, moving with fish from barracuda to leopard sharks and mantas, conditions can change quickly. Well worth diving.
Raymond Willings, Scotland
In the Similan islands: white tip sharks and good night dives"
60 kilometres away from the mainland, the Surin Islands include some of the best diving in Thailand. There are five islands in the group, all within the Mu Ko Surin National Park. During the rainy season, from May to October, the park is closed. The diving season runs from December and April, with chances of whale shark sightings from February onward.
The best way to dive the Surin Islands is by liveaboard. These often leave from around Khao Lak and take in both the Similans and the Surins. Some leave from Phuket and finish at Khao Lak - or vice versa.
One liveaboard that stands out is The Junk. Smaller than most it has featured in the James Bond film The Man with the Golden Gun.
The most famous dive site in the Surin archipelago is Richelieu Rock. Rightly so as it is a world class dive site. The rock is 10 km away from the nearest island and 80 km northwest of Khao Lak. A pinnacle, it rises to the surface from 30 m. It is beautiful dive. Covered in colourful soft corals it is a haven for many unusual small creatures like sea horses, frogfish, harlequin shrimp, ghost pipefish and nudibranchs. But there is not only the delight of spotting one of these, its remote location means the reef is visited by whale sharks, manta rays, tuna and great barracuda.
Frogfish. Photo credit: Arhnue Tan/Pixabay
" Rich marine life. Challenging but worth it
Serena, 4 May 2018
"Beautiful, colourful diving. Saw seahorses, cuttlefish, muraenas. I remember I took so many beautiful photos.
Celia, 26 March 2018
"Manta ray, coral and colorful fish.
Adriaan Jelsma, 27 March 2017
"Pinnacle Reef dive. Extremely colourful reef with large schools of fish including Tuna, Jacks, Barracuda, down to Seahorses and Mantis Shrimps and the chance to see Whaleshark and Manta, unfortunately after I had been
Jim Jones, 23 June 2014
"A horse shoe of rocky pinnacles, just breaks the surface at low tide. Famous for Whale shark sightings, but also great for big schools of pelagic fish such as jacks, barracuda and batfish. Mantas are also seen, and it is a superb spot for Macro photography, with such critters as ghost pipefish, harlequin shrimp, frogfish, seahorses. Currents can be strong, but an experienced guide can keep you in the shelter. Depth maximum about 30 m. Needs several dives to see the whole area."
"Top site for whale sharks in the Andaman sea. Rocky outcrop that rises from the bottom 30 m to just over a meter out of the water in low tide."
"My best dive so far, among all those rarities found there the only thing we lacked was the Whale Sharks.
Calle Nilsson, Sweden, 2011
"Richelieu rock was pretty astounding and would be worth visiting multiple times as on a live-aboard.
Simon Dragland, 2008
"Superb Viz: 3 dives 3 Whale Shark Sightings... Descending for the first time was like entering a giant underwater cathedral.. amazing sites and a monumental array of marine life.. Excellent Diving all round
Sam Seed, UK
Dive 1 two mantas. Dive 2 whale sharks and mantas.
Robert Marshall, 2021
Part of the Samui archipelago, Koh Tao offers the best diving in the Gulf of Thailand. There are deep, pinnacle dives and gradually sloping reefs. However, the sites can become very crowded.
Recently researchers investigated the health of corals around the island. They found that the coral around little dived sites was much healthier than that at the popular diving areas. The scientists concluded that better management needed to be put in place to protect the corals.
Some of the dive sites of Koh Tao - Little dived sites are shown in white, popular dive sites in black
For dive centres in Koh Tao see our Gulf of Thailand Dive Operators page.
"We have just
returned from 2 weeks diving in Koh Tao staying at Koh Nangyuan. The
islands are spectacular and truly idyllic. Best dive was Chumphon
Pinnacle but after doing 8 dives at various sites including Japanese
gardens, Green Rock, The Twins and White Rock we left feeling
disappointed. A lot of the dives are very similar but more importantly
there were divers everywhere. At Chumphon Pinnacle one day there were
over 40 divers and it was very easy to almost lose my buddy on several
occasions. Perhentian Islands in Malaysia were much better with lots
less people and better marine life, but both certainly do not beat
anywhere on the Barrier Reef.
"A lot of different dive sites and all of them are splendid! Japanese
Gradens with the most beautiful coral, Twin Peaks with all the fish,
"We have just
returned from a week's diving in Koh Tao (the place famous for Trevor
the Trigger fish , which we didn't see and also regular whale shark
spottings, which we didn't see either!) but the diving out there was
amazing with plenty to look at, great visibility and I can highly
recommend Carabao Dive Shop. If you are
going out there pop in and do your diving with them as there is quite
a lot of competition out there with dive shops and some ...no names
....just have loads of people packed onto the boats. "
I went to Thailand diving for the first time. I did my courses in Koh Tao and enjoyed it so much I went on to do my Advanced. I dived with Blue Planet. I found them very helpful and had a really good instructor who helped me get some magnificent photos. I went on a trip to the Similan islands with them and had the best time of my life. So am going back in november again to move on to my rescue course and hopefully move on all the way. I would give advice to any body that has not dived there before to give it a try as the underwater sea life there was overwhelming with large beautiful sea fern, large manta rays up to 4m and lots of trumpet fish which are my personal favorite, I could go on about it all day. Also humpback whales where surface all over it was great. Thanx blue planet for introducing me to the new world."
"I went to Ko Tao, where I started to do my Open Water. The visibility was good, however there were so many people and very little to see. I went snorkelling in Redang (off the coast of Malaysia) and saw more fish/ sharks/ eels, etc. The only thing the island had to offer was cheaper rates on dive certification. I also dove around Ko Phi Phi... now that was amazing! I saw a leopard shark, lion fish, giant moray, butter fly fish, blue ring, and many more! I would recommend the diving off Phi Phi over Ko Tao any day!"
"Ko Tao was disappointing by contrast with Koh Phi Phi and Richelieu rock. It was overcrowded with weak visibility and was frankly a bit boring although relatively cheap."
"US WWII Sub torpedoed in S China Sea by Jap mine layer. Lost until about 2008. Depth = about 270-300' to the sand.
Paul Ludwick, January 2019
Four underwater pinnacles. The top of the shallowest is at 16 m and the bottom at 34 m. The pinnacles attract many pelagic fish: barracuda, trevally and even sometimes whale sharks. There may be heavy-duty currents
"A bit more far out..like twenty minutes by boat. But boy it was worth it - saw some really huge groupers!
Peter, 9 February 2017
Advanced divers with larger pelagic fish and occasional Whale Sharks"
John Baker, Samui Dive Tribe, 2016
I learned to dive on Koh Tao with Seashell Divers. It was amazing, the highlight being the Chumphon Pinnacle. Vibrant coral reaching from the sea bed 30 m below the surface, with the sun glinting off shoals of fish all around. I've now dived on Koh Phi Phi and Cozumel (Mexico), and I have yet to see such varied life in one place. Especially amazing for new divers. Koh Tao is a beautiful and cheap place to do dive courses. I can't wait to go back--still haven't seen my whale shark!
Brad Bonnell, 2012
"Two pinnacles. Lots of marine life. Has a buoyancy park and coral conservation project too."
David Dulson, 2012
"Rocky bay and coral garden. A series of small swim-throughs. Lots of giant clams and fusilier fish."
David Dulson, 2012
"Nice wreck which was sunken on purpose - easy to dive also for beginners
Peter, 9 February 2017
"Shallow but good and relaxing for the last dive
Peter, 9 February 2017
The best conditions for diving around Pattaya are between November and March, but there is diving all year round. It gets very busy at weekends being the nearest diving to Bangkok. The diving at the far islands is better than that at the near islands.
For dive centres in Pattaya see our Thailand Dive Operators page.
Quite often vis not great - but does not have the 'dive factory' feel as Koh Tao . HMS Khood is always worth a dive, sitting plumb at 27 m. Some nice barracuda, tuna and perhaps a turtle, but all in all not disappointing. Several comments have been made about the increasing amount of rubbish in the sea, both from Pattaya and Koh Larn. Many dive operators are a touch on the expensive side (compared with the rest of Asia) but after all it is Pattaya.
After living in Pattaya area for 4 months and diving every few days, that is the last place I would ever go. Too often there were dead fish on the wrecks from fisherman using blasting caps to fish, along with various substances - including the not so infrequent condom floating in the water. Again, this was all offsite - not simply at the Pattaya or Jomtien shoreline. Convenient from Bangkok ...YES. Worth getting in the water...NO.
This marine national park, some 650 km2 covers 52 islands to the east of the Gulf of Thailand, near the Cambodia border. Koh Chang itself is the second largest island in Thailand. The best diving here is from November to May.
For dive centres see our Thailand Dive Operators page.
"Beautiful coral garden.
Wilma Willems, The Netherlands, 5 September 2012
"A lot of barracuda, triggerfish, fusilier etc!"
Wilma Willems, The Netherlands, 5 September 2012
The Andaman Islands lie between Burma and India. They belong to India so we've covered the diving there in our India section.
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1Control Measures for Tourism Entrepreneurs in Marine National Parks - SCUBA Diving and Related Activities in Marine National Parks, Department of National Parks, Wildlife and Plant Conservation.
2Marine National Park Thailand Tsunami document
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