Diving in Thailand: The Complete Guide

Thailand is one of the easiest places in the world to go diving. The water is warm all year, dive shops are everywhere, courses are good value, and a dive trip combines easily with a beach holiday. The country has two coastlines on two different seas, and each has its own diving season, so you can dive somewhere in Thailand in any month.

This guide covers how to choose a coast for your dates, the sites worth travelling for, how to get certified, and how to stay safe.

Two coasts, two seasons

The most important decision is which coast to dive, and your travel dates largely make it for you.

	Andaman Sea (west coast)	Gulf of Thailand (east coast)
Main bases	Khao Lak, Phuket, Koh Phi Phi, Koh Lanta, Koh Lipe	Koh Tao, Koh Samui, Koh Phangan, Pattaya, Koh Chang
Best season	Roughly November to April	Year-round; usually best from around March to September
Off season	Southwest monsoon, roughly May to October. Rough seas, and the Similan and Surin national parks close	Northeast monsoon, roughly October/November to December
Typical visibility	15–30 m+, often better offshore	10–25 m, varies with plankton and weather
Known for	Big pelagics, granite boulders, soft corals, liveaboards	Training, pinnacles, whale sharks, budget diving

Seasons shift a little from year to year. If you’re travelling at the edge of a season, check with dive shops on that coast before you book.

The Andaman Sea

The Andaman coast has Thailand’s best-known dive sites. The diving is offshore, the water is clear, and the topography is dramatic.

Similan Islands

The Similan Islands National Park lies about 60–70 km off Khao Lak. It’s famous for huge granite boulders that form swim-throughs, arches and canyons on the west side of the islands, and for gentler sloping reefs on the east side. Well-known sites include Elephant Head Rock, Christmas Point and East of Eden.

• Season: the park normally opens in mid-October and closes in mid-May.
• How to dive it: a liveaboard of three to five days from Khao Lak or Phuket is the classic option. Long day trips by speedboat run from Khao Lak.
• Nearby: Koh Bon is known for manta rays. Koh Tachai sometimes has whale sharks, but it has been closed in some seasons so the reef can recover.

Richelieu Rock and the Surin Islands

Richelieu Rock is a horseshoe-shaped pinnacle in the Mu Ko Surin National Park. Many divers rate it the best single site in Thailand. It’s covered in purple soft coral, and it’s a macro paradise, with seahorses, harlequin shrimp, frogfish and ghost pipefish. Whale sharks also turn up here.

Most divers reach it on a Similan liveaboard that includes the northern sites. Day trips run from Khuraburi, but the boat ride is long.

Phuket

Phuket is the easiest Andaman base: it has an international airport, plenty of hotels and dozens of dive operators. Day trips go to:

• Racha Yai and Racha Noi: relaxed reef dives for beginners at Racha Yai, with stronger currents and bigger fish at Racha Noi.
• Shark Point and Anemone Reef: reefs covered in soft corals, known for leopard sharks (zebra sharks).
• King Cruiser wreck: a car ferry that sank in 1997. It now has a lot of marine life, but it is deteriorating, so stay outside unless you’re trained and guided for penetration.

Koh Phi Phi

Phi Phi’s limestone cliffs continue underwater as walls and caves. Bida Nok and Bida Nai are the signature sites, with reef sharks, turtles and big schools of fish. Phi Phi is also a good place for an Open Water course with a view.

Koh Lanta: Hin Daeng and Hin Muang

Hin Daeng and Hin Muang are two remote pinnacles south of Koh Lanta, and they’re among the most exciting dives in the country. Hin Muang has walls covered in purple soft coral that drop well below recreational depths. Both sites attract manta rays and the occasional whale shark. Expect current: these sites suit divers with some experience.

Koh Lipe

Koh Lipe is near the Malaysian border, in Tarutao National Marine Park. It has quieter dive sites with healthy soft corals, and a laid-back island to come back to. Popular sites include Stonehenge and Eight Mile Rock.

The Gulf of Thailand

The Gulf has calmer, shallower water and the best-value diving in the country. It’s also where most people in Thailand learn to dive.

Koh Tao

Koh Tao (“Turtle Island”) is one of the busiest places in the world to get certified. The small island has dozens of dive schools, and many sites are only a short boat ride away. That makes it ideal for courses and for building experience quickly.

• Chumphon Pinnacle: a granite pinnacle covered in anemones. Big schools of barracuda and trevally live here, and whale sharks visit in some seasons.
• HTMS Sattakut: a WWII-era landing craft that was scuttled as an artificial reef in 2011. It’s an accessible wreck dive for newer divers.
• Shark Island, Twins and Japanese Gardens: shallow, easy sites for training and fun dives.

Sail Rock

Sail Rock sits between Koh Tao and Koh Phangan, and it’s the Gulf’s best dive site. It’s a single pinnacle rising from about 40 m, with a vertical swim-through called the Chimney, dense schools of fish, and one of the better chances of seeing a whale shark on this coast. Boats run there from Koh Tao, Koh Phangan and Koh Samui.

Pattaya and Koh Chang

Pattaya and Koh Chang are both within easy reach of Bangkok, and both are known for wreck diving. Pattaya has the scuttled navy ships HTMS Khram, HTMS Kut and HTMS Mattaphon. Koh Chang has the HTMS Chang, which was scuttled in 2012. Visibility is lower than on the islands, but these trips work well if you only have a weekend in Bangkok.

Liveaboard or day trips?

	Liveaboard	Day trips
Best for	Similan, Surin, Richelieu Rock, Koh Bon	Phuket, Phi Phi, Lanta, Koh Tao, Samui
Dives per day	Usually 3–4, including night dives	Usually 2
Pros	Reaches remote sites at the best times; you mostly just eat, sleep and dive	Flexible and cheaper; time on land with non-diving partners
Cons	Costs more; fixed itinerary; not ideal if you get seasick	Long boat rides to offshore sites; more divers at popular sites

If the Similans and Richelieu Rock are on your list and your dates are between November and April, a liveaboard is worth it.

Getting certified in Thailand

Thailand is a great place to learn. The water is warm and calm, the instructors are experienced, and courses cost less than in most of the world. The main agencies (PADI, SSI and RAID) are widely available.

• Open Water (beginners): usually 3–4 days of theory, confined water practice and four open water dives. It certifies you to dive to 18 m.
• Advanced Open Water: 2 days and five adventure dives, including a deep dive to 30 m and navigation. It’s worth doing before deeper Andaman sites such as Hin Daeng.
• Specialties: Nitrox is especially useful on liveaboards. Other options include wreck, deep and underwater photography.

Koh Tao is the classic place to learn. Phuket, Khao Lak, Phi Phi and Koh Lanta all have plenty of good schools too. Choose an operator for its safety culture and small group sizes, not only for the cheapest price.

What you’ll see

• Whale sharks: reported on both coasts. Richelieu Rock, Koh Tachai, Hin Daeng, Sail Rock and Chumphon Pinnacle are the best-known spots. Sightings are never guaranteed.
• Manta rays: Koh Bon, Koh Tachai, Hin Daeng and Hin Muang, mostly in the Andaman high season.
• Leopard sharks: sandy bottoms near Phuket and Phi Phi.
• Turtles: hawksbill and green turtles at many sites, including around Koh Tao.
• Macro: seahorses, harlequin shrimp, frogfish, ghost pipefish and nudibranchs, especially at Richelieu Rock.

Gear and water conditions

• Water temperature: usually about 27–30 °C. A 3 mm shorty or full suit is plenty for most people. Some divers who get cold easily prefer a full 3 mm suit for repeated dives.
• Rental gear is widely available and usually decent. Bring your own mask and dive computer if you have them.
• Reef-safe sunscreen: Thailand bans sunscreens containing oxybenzone, octinoxate, 4-MBC and butylparaben in its marine national parks. Use a mineral sunscreen, or cover up with a rash guard.
• Seasickness: some offshore crossings are rough. If you’re prone to seasickness, take tablets before you board.

Safety essentials

• Get dive insurance. Standard travel insurance often excludes scuba diving or caps the depth it covers. Specialist cover, such as DAN, pays for evacuation and recompression treatment.
• Know where the chambers are. There are recompression facilities in places such as Phuket, Koh Samui, Koh Tao and Pattaya. Remote liveaboard sites can still be many hours away from one.
• Don’t fly too soon after diving. Common guidance is to wait at least 12 hours after a single no-decompression dive, and 18 hours after multiple dives or multiple days of diving. Longer is better.
• Respect currents. Sites like Hin Daeng, Richelieu Rock and Chumphon Pinnacle can have strong currents. Carry a surface marker buoy (SMB) and listen to the briefing.
• Dive within your training, and log some easy dives first if you haven’t dived for a while.

Diving responsibly

Thailand’s reefs have been hit by coral bleaching events and heavy tourism. A few habits make a real difference:

• Keep your buoyancy under control, and don’t touch, kick or stand on coral.
• Don’t feed or chase marine life, and never ride turtles or touch whale sharks.
• Don’t buy shells, coral or turtle-shell souvenirs.
• Pay national park fees willingly, because they fund protection and the seasonal closures that let reefs recover.
• Choose operators that brief on reef etiquette and use mooring lines rather than anchoring on reefs.

Sample itineraries

One week on the Andaman coast (November to April)

1. Fly into Phuket and transfer to Khao Lak.
2. Do a 4-day / 4-night Similan liveaboard that includes Koh Bon, Koh Tachai (if it’s open) and Richelieu Rock.
3. Finish with a day of Phuket diving or beach time. Leave the last 24 hours free before your flight home.

Ten days in the Gulf (March to September)

1. Take the ferry to Koh Tao via Chumphon or Koh Samui.
2. Do an Open Water or Advanced course, then fun dive Chumphon Pinnacle and the Sattakut wreck.
3. Do a day trip to Sail Rock, then unwind on Koh Phangan or Koh Samui.

Quick FAQ

Can I dive in Thailand all year? Yes. Dive the Andaman coast from roughly November to April and the Gulf for most of the rest of the year. Koh Tao and the Gulf islands have diving in almost every month.

Do I need to be certified to try it? No. Most shops run a Discover Scuba Diving or Try Dive. You do a short briefing, then a shallow, supervised dive with an instructor.

Which is better for beginners, Koh Tao or Phuket? Both work well. Koh Tao is cheaper, has calm sites close to shore, and has a strong diving community. Phuket is easier to reach and has more non-diving activities.

What’s the single best dive site in Thailand? Most divers say Richelieu Rock. Hin Daeng, Hin Muang, Koh Bon and Sail Rock all have their fans.

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Conditions, park opening dates and regulations change. Confirm the details with your dive operator and the national park authorities before you travel. Have a great trip, and enjoy the bubbles.