Scuba Diving in Thailand Beyond Koh Tao: 8 Underrated Dive Sites (2026)

Koh Tao is where Southeast Asia learns to dive. Every year tens of thousands of backpackers get their Open Water certification there, and for good reason: it is absurdly cheap, the island is beautiful, and the dive schools are set up like factories — efficient, competitive, and designed to move beginners through the PADI system fast.

But here is the thing nobody tells you in Sairee Beach: Koh Tao is not great diving. It is great training diving. The visibility is often mediocre (5-15 meters on an average day), the reefs have taken a beating from decades of mass tourism, and the marine life, while decent, does not compare to what is happening an overnight boat ride away.

If you got your card on Koh Tao and thought "that was fun but nothing like the photos," you were not doing it wrong. You just have not been to the sites that experienced divers travel to Thailand specifically for.

This guide covers eight dive areas beyond the Koh Tao bubble — from the gin-clear waters of the Similan Islands to the deep walls of Hin Daeng where visibility can stretch past 30 meters and whale sharks cruise through like they own the place. Because they do.

Quick Context: Thailand's Two Dive Coasts

Thailand's diving splits across two bodies of water with completely different seasons, conditions, and character.

Andaman Sea (West Coast): Phuket, Krabi, Similan Islands, Koh Lipe. Best diving October through May. The monsoon (June-September) closes most dive sites and cancels all liveaboard trips. When conditions are good, the Andaman side offers Thailand's best visibility, healthiest coral, and biggest pelagic encounters.

Gulf of Thailand (East Coast): Koh Tao, Koh Samui, Koh Phangan, Chumphon. Diveable year-round, but best March through October. Visibility is generally lower than the Andaman side (the Gulf is shallower and more nutrient-rich), but the upside is that some Gulf sites are accessible 365 days a year.

The key takeaway: Your dive trip timeline should dictate which coast you hit. Planning for December through April? The Andaman side is in peak condition. Visiting July through September? The Gulf is your only option because the Andaman is blown out.

For island-hopping logistics across both coasts, check the Thailand island ferry guide.

The 8 Dive Sites That Make Koh Tao Look Like a Swimming Pool

1. Similan Islands (Liveaboard Territory)

The headline: Thailand's best diving, full stop. Nine granite islands roughly 70 kilometers off the Phang Nga coast, protected as a national park since 1982. The Similans consistently rank among the top 10 dive destinations in the world, and once you are underwater there you will understand why.

What makes it special: The visibility is absurd. On a good day you are looking at 25-40 meters of crystal clear water with massive granite boulders covered in soft corals, swim-throughs, and enough fish life to make your head spin. Manta rays are common at certain sites (particularly Koh Bon), and the deeper pinnacles attract everything from barracuda schools to reef sharks.

How to get there: Almost exclusively by liveaboard. The islands are too far from shore for comfortable day trips. Most liveaboards depart from Khao Lak (the launch town north of Phuket) and run 2-4 night itineraries that include 10-14 dives.

Key dive sites within the Similans:

Christmas Point (Island 9): Huge boulder formations, soft coral gardens, swim-throughs. The signature Similan dive.
Elephant Head Rock (Island 8): Massive underwater rock formations creating archways and tunnels. Moderate to strong currents.
Koh Bon (West Ridge): The manta ray cleaning station. October through April, mantas are almost a certainty here.
Deep Six (Island 7): Stunning wall dive dropping to 30+ meters. Leopard sharks rest on the sandy bottom.

Season: Open mid-October through mid-May only. The national park physically closes during monsoon season. No exceptions.

Cost: 3-day/2-night liveaboard from Khao Lak runs 15,000-25,000 THB ($420-$700 USD) including all dives, food, accommodation on the boat, and park fees. Premium operators with nitrox and better boats push toward 30,000 THB ($840 USD).

Minimum certification: Open Water for most sites. Advanced Open Water recommended for the deeper dives at Koh Bon and Elephant Head where currents get serious.

2. Richelieu Rock (The Crown Jewel)

The headline: A single horseshoe-shaped pinnacle rising from the Andaman Sea floor, roughly 200 kilometers from Phuket. Richelieu Rock is regularly cited as the single best dive site in Thailand and one of the top five in all of Southeast Asia.

What makes it special: This is where you go for the big stuff. Whale sharks appear here between February and May (with peak sightings in March and April), and they are not rare — operators report whale shark encounters on roughly 30-40% of visits during peak season. Manta rays cruise through year-round during the open season. The rock itself is covered in purple and red soft corals so dense it looks painted, and the macro life is equally impressive: ornate ghost pipefish, harlequin shrimp, seahorses, and frogfish hide in every crevice.

How to get there: Liveaboard only. Richelieu Rock is typically included on 4-day Similan liveaboard itineraries that extend north into the Surin Islands area. Some operators run dedicated Richelieu-focused trips.

The experience: You descend onto what looks like an unremarkable rock formation, and then the life starts revealing itself. Schools of barracuda swirl overhead. Batfish drift past in formation. If you are lucky, the water darkens slightly and a whale shark materializes from the blue — 8 to 12 meters of spotted gentle giant, close enough to see the remoras hitching a ride on its belly.

Season: Same as Similans — mid-October through mid-May. Whale shark peak is February through April.

Cost: Included in most 4-day/3-night Similan liveaboard packages (20,000-35,000 THB / $560-$980 USD). Dedicated Richelieu trips from Khao Lak run slightly higher.

Minimum certification: Advanced Open Water strongly recommended. Currents can be unpredictable and the best action often happens at 25-30 meter depth.

3. Koh Lipe and Tarutao National Park (The Uncrowded Andaman)

The headline: Thailand's southernmost dive area, sitting just 60 kilometers from the Malaysian border. While the Similan liveaboards get packed during peak season, Koh Lipe's dive sites remain comparatively empty because most divers never make it this far south.

What makes it special: Tarutao National Marine Park encompasses over 50 islands with healthy, minimally impacted reefs. The coral here has not been hammered by decades of mass tourism the way Koh Tao and even parts of the Similans have. Visibility ranges from 15-30 meters, and the marine life diversity is outstanding — everything from reef sharks to sea turtles to ornate cuttlefish.

Key dive sites:

8 Mile Rock: Offshore pinnacle with consistent large pelagic sightings. Strong currents attract barracuda, trevally, and occasional whale sharks.
Stonehenge: Named for its boulder formations. Sea turtles, lionfish, moray eels, and stunning soft coral.
Koh Hin Ngam (Coral Garden): Shallow, colorful, perfect for photography and less experienced divers.

How to get there: Fly to Hat Yai (from Bangkok on AirAsia or Nok Air, typically 1,200-2,500 THB / $34-$70 USD), then minivan to Pak Bara pier (2 hours), then speedboat to Koh Lipe (1.5 hours). It is a journey, which is exactly why the reefs are in better shape. Check the island ferry guide for current Koh Lipe ferry schedules.

Season: Mid-October through May. The island essentially shuts down during monsoon — most resorts and dive shops close entirely.

Cost: Day trip diving from Koh Lipe runs 2,800-4,500 THB ($78-$126 USD) for two dives including equipment. Fun dives without rental gear drop to around 2,200 THB ($62 USD). Significantly cheaper than Similan liveaboards.

Minimum certification: Open Water is fine for most sites. 8 Mile Rock requires Advanced Open Water.

4. Koh Phi Phi (Leopard Sharks and Anemone Reef)

The headline: Yes, Phi Phi is famous for Maya Bay and Instagram crowds. But the diving around these limestone karst islands is genuinely excellent, and most of the tourists snorkeling at the surface have no idea what is happening 20 meters below them.

What makes it special: Koh Phi Phi sits in the middle of several premier dive sites that offer different experiences. The signature encounter is leopard sharks (also called zebra sharks) — docile, spotted bottom-dwellers that rest on sandy patches around Phi Phi Ley and Shark Point. They are not dangerous and they are not rare. Seeing three or four on a single dive is normal during peak season.

Key dive sites:

Anemone Reef (Hin Jom): A submerged pinnacle absolutely carpeted in anemones with resident clownfish colonies. Stunning wide-angle photography site.
Shark Point (Hin Musang): Three submerged pinnacles stretching over 200 meters. Leopard sharks on the sand, soft coral on the rocks, and schools of fusiliers above.
Koh Bida Nok: Wall dive dropping to 28 meters with blacktip reef sharks patrolling the deeper sections. Seahorses and ghost pipefish in the shallows.
The King Cruiser Wreck: A car ferry that sank in 1997 after hitting Anemone Reef. Now a thriving artificial reef at 12-32 meters depth. Lionfish, scorpionfish, and barracuda own this wreck.

How to get there: Day trip boats depart daily from Koh Phi Phi Don. You can also dive these sites as day trips from Phuket or Ao Nang (Krabi), though the boat ride is longer (90 minutes versus 20 minutes from Phi Phi).

Season: November through April for best conditions. Diveable into May, but visibility drops. Closed or limited during monsoon months.

Cost: Two-dive day trips from Phi Phi run 3,000-4,500 THB ($84-$126 USD) with equipment. Operators in Tonsai Village are competitive — shop around. Phuket-based day trips to the same sites cost more (4,500-6,500 THB / $126-$182 USD) because of the longer boat transfer.

Minimum certification: Open Water for most sites. King Cruiser wreck penetration requires Advanced Open Water.

5. Chumphon Pinnacle (Advanced Koh Tao)

The headline: Technically accessible from Koh Tao (it is about 40 minutes by boat from the island), but Chumphon Pinnacle is a completely different experience from the shallow reef dives that Open Water students do around Mae Haad and Japanese Garden.

What makes it special: This is a deep granite pinnacle rising from 40 meters to within 14 meters of the surface. The currents here attract large pelagic species that you simply do not see on Koh Tao's standard dive sites: giant grouper, large barracuda schools, batfish in the hundreds, and — during the right season — whale sharks. Chumphon Pinnacle is the Gulf of Thailand's most reliable whale shark encounter, with sightings concentrated between March and June.

The dive: You descend through blue water onto the pinnacle, which is covered in anemones so thick it looks like an underwater garden. The current can be strong, which means you are often hooking into the rock and watching the show roll past you. It is not a relaxing dive. It is a spectacular one.

How to get there: All Koh Tao dive shops offer Chumphon Pinnacle as a day trip. It is their flagship advanced dive. If you are already on Koh Tao getting certified, adding Chumphon Pinnacle to your trip is the obvious next step. Read the getting to Koh Tao guide for transport logistics.

Season: Best March through October. Whale shark season peaks March through June. Diveable year-round but visibility varies.

Cost: Fun dive to Chumphon Pinnacle from Koh Tao runs 1,200-1,800 THB ($34-$50 USD) per dive — still the cheapest diving in Thailand by a wide margin.

Minimum certification: Advanced Open Water recommended. Depths reach 30+ meters and currents can be unpredictable. Some shops will take Open Water divers but limit them to the shallower sections (14-18 meters).

6. Sail Rock (Hin Bai)

The headline: A massive pinnacle in the middle of the Gulf of Thailand, roughly equidistant between Koh Tao and Koh Phangan. Sail Rock is widely considered the single best dive site in the Gulf, and it delivers encounters that rival anything on the Andaman side.

What makes it special: Sail Rock is a whale shark corridor. Between March and June, whale sharks pass through this area with surprising regularity. But even without the whale sharks, this site is exceptional. The pinnacle rises from 40 meters to break the surface (the "sail" is visible above water), and it features a massive vertical chimney — a natural swim-through that you can enter at 19 meters and exit at 6 meters, ascending through a column of light with fish swirling around you. It is one of the most dramatic underwater experiences in Thailand.

The dive: The standard route descends to the chimney entrance, passes through it, then circuits the pinnacle at depth before ascending along walls covered in barrel sponges, anemones, and soft corals. Large groupers lurk in the overhangs. Batfish school in the hundreds. On good days, the visibility opens up to 20+ meters and you can see the entire pinnacle structure from mid-water.

How to get there: Day trips run from both Koh Tao (50 minutes by boat) and Koh Phangan (40 minutes). Some Koh Samui operators also make the run, but it is a longer transfer.

Season: Diveable year-round. Best visibility and whale shark chances March through June. October through December can bring reduced visibility but stronger currents that concentrate fish life.

Cost: Day trips from Koh Tao run 1,500-2,200 THB ($42-$62 USD) per dive. From Koh Phangan, expect 2,500-3,500 THB ($70-$98 USD) for a two-dive trip. Koh Phangan prices are higher because the dive industry there is smaller and less competitive.

Minimum certification: Advanced Open Water recommended. The chimney swim-through requires comfort with confined spaces at depth, and the open water sections can have strong currents.

7. Hin Daeng and Hin Muang (Thailand's Deepest Wall Dive)

The headline: Two submerged pinnacles in the open Andaman Sea, roughly 60 kilometers southwest of Koh Lanta. Hin Muang ("Purple Rock") features Thailand's deepest wall dive — a sheer vertical drop from 8 meters to 60+ meters — and Hin Daeng ("Red Rock") sits nearby with equally impressive topography and marine life.

What makes it special: These sites are open ocean. There is no island nearby, no shallow reef system, just deep blue water and two pinnacles rising from the abyss. This isolation is what makes the diving extraordinary. Manta rays are common (Hin Daeng has a known cleaning station), reef sharks patrol the walls, and the soft coral coverage — particularly the deep red and vivid purple varieties that give the sites their names — is among the most photogenic in Thailand.

The experience at Hin Muang: You roll off the boat into blue water and descend onto the top of the pinnacle at 8 meters. The wall drops away below you into darkness. At 25-30 meters, the soft coral becomes dense and the colors are vivid even without a torch (though bring one — the reds and purples explode under artificial light). Reef sharks cruise along the wall. Look into the blue for mantas.

How to get there: Day trips from Koh Lanta (2-2.5 hours by boat). Some operators run from Koh Phi Phi, but the transfer is longer. Weather conditions must be good — the open ocean location means these sites close frequently during marginal weather even within the official season.

Season: November through April. These sites are weather-dependent even during season — rough seas cancel trips regularly in November and late April.

Cost: Day trips from Koh Lanta run 4,000-5,500 THB ($112-$154 USD) for two dives. The higher price reflects the long boat transfer and fuel costs. Premium operators with smaller groups charge more.

Minimum certification: Advanced Open Water required. This is not negotiable. The depths, currents, and open-ocean conditions make this unsuitable for recently certified divers. Many operators require a minimum of 30 logged dives.

8. Koh Chang (Wrecks and the Quiet Gulf)

The headline: Thailand's second-largest island, tucked into the far eastern corner of the Gulf near the Cambodian border. Koh Chang's diving is not world-class by Similan standards, but it offers something no other Thai dive area does: wreck diving in warm, accessible water with almost no other divers around.

What makes it special: The HTMS Chang — a decommissioned Thai Navy ship deliberately sunk in 2012 as an artificial reef — sits upright in 30 meters of water off the southern coast of the island. At 100 meters long, it is one of the largest diveable wrecks in Southeast Asia. The ship has been colonized by marine life at impressive speed: groupers nest in the bridge, barracuda circle the mast, and the hull is crusting over with hard and soft corals.

Beyond the wreck, Koh Chang's reef diving is modest but pleasant. Koh Rang National Marine Park, a cluster of smaller islands south of Koh Chang, has decent reef systems with good turtle sightings and healthy hard coral.

How to get there: Bus from Bangkok's Eastern (Ekkamai) terminal to Trat (5-6 hours, 250-350 THB / $7-$10 USD), then ferry to Koh Chang (30 minutes). Flights to Trat exist on Bangkok Airways but are expensive. The Thailand islands itinerary guide covers eastern island logistics.

Season: Best November through May, but diveable year-round. Visibility is typically 8-20 meters — decent but not exceptional.

Cost: Two-dive day trips from Koh Chang run 3,000-4,000 THB ($84-$112 USD) with equipment. Wreck-specific dives cost slightly more (3,500-5,000 THB / $98-$140 USD). There are only a handful of dive shops on Koh Chang, so prices are less competitive than Koh Tao.

Minimum certification: Open Water for reef dives around Koh Rang. Advanced Open Water required for the HTMS Chang wreck (30 meters depth, overhead environment on penetration dives).

Comparison Table: All 8 Dive Areas at a Glance

| Dive Area | Best For | Visibility | Depth Range | Cost Per Dive (THB) | Cost Per Dive (USD) | Best Season | Highlight Species | |-----------|----------|-----------|-------------|---------------------|---------------------|-------------|-------------------| | Similan Islands | World-class reef + pelagic | 25-40m | 5-40m | 4,000-7,000 (liveaboard per dive) | $112-$196 | Oct-May | Manta rays, reef sharks, barracuda | | Richelieu Rock | Whale sharks, macro | 15-30m | 5-35m | 5,000-8,000 (liveaboard per dive) | $140-$224 | Oct-May (whale sharks Feb-Apr) | Whale sharks, manta rays, ghost pipefish | | Koh Lipe / Tarutao | Uncrowded healthy reefs | 15-30m | 5-30m | 1,400-2,250 | $39-$63 | Oct-May | Sea turtles, reef sharks, cuttlefish | | Koh Phi Phi | Leopard sharks, wrecks | 10-25m | 5-32m | 1,500-3,250 | $42-$91 | Nov-Apr | Leopard sharks, clownfish, lionfish | | Chumphon Pinnacle | Budget advanced diving | 10-25m | 14-40m | 1,200-1,800 | $34-$50 | Mar-Oct | Whale sharks, giant grouper, batfish | | Sail Rock | Best Gulf site, chimney | 10-25m | 6-40m | 1,500-2,200 | $42-$62 | Year-round (best Mar-Jun) | Whale sharks, barracuda, grouper | | Hin Daeng / Hin Muang | Deep wall dive, mantas | 15-30m | 8-60m+ | 2,000-2,750 | $56-$77 | Nov-Apr | Manta rays, reef sharks, soft coral | | Koh Chang | Wreck diving, quiet | 8-20m | 5-30m | 1,500-2,500 | $42-$70 | Nov-May | Wreck marine life, sea turtles |

Liveaboard vs Day Trips: Which Makes Sense?

This is the single most important logistical decision for diving beyond Koh Tao.

When a Liveaboard Is Worth It

For the Similan Islands and Richelieu Rock, there is no real alternative. The sites are too far offshore for comfortable day trips. A few Phuket-based operators run day trips to the outer Similans, but you spend 4+ hours on a speedboat each way, arrive tired, and get 2-3 dives before the long ride back. The liveaboard gives you 10-14 dives over 2-4 nights, early morning dives when the light is best, night dives, and you wake up already at the dive site.

Typical 3-day/2-night Similan liveaboard:

15,000-25,000 THB ($420-$700 USD)
Includes: 10-12 dives, all meals, cabin accommodation, park fees
Departs: Khao Lak (Tab Lamu pier)
Budget-friendly operators: MV Giamani, MV Pawara, Similan Diving Safaris
Premium operators: The Junk, Manta Queen fleet (nitrox included)

Typical 4-day/3-night Similan + Richelieu liveaboard:

20,000-35,000 THB ($560-$980 USD)
Includes: 14-18 dives, Similan + Koh Bon + Koh Tachai + Richelieu Rock
This is the itinerary that serious divers fly to Thailand for

When Day Trips Make More Sense

For everything else on this list — Phi Phi, Sail Rock, Chumphon Pinnacle, Hin Daeng/Hin Muang, Koh Chang, Koh Lipe — day trips are the standard and often the only option. You are based on an island (or coastal town), boats depart in the morning, you do 2-3 dives, and you are back by afternoon.

Day trip advantages:

Flexibility — dive when conditions are good, skip when they are not
No seasickness risk from sleeping on a rocking boat
Choose your own accommodation (hostel dorm versus liveaboard bunk)
Mix dive days with non-dive activities

Day trip disadvantages:

Limited to 2-3 dives per day
No early morning or night dives at remote sites
More surface time traveling between sites

Costs: PADI Courses and Fun Dives Beyond Koh Tao

Everyone knows Koh Tao has the cheapest diving in the world. But how much more does it cost once you leave the island? Here is the honest breakdown for 2026.

PADI Courses

| Course | Koh Tao Price | Other Locations | Notes | |--------|---------------|-----------------|-------| | Open Water (3-4 days) | 8,500-10,000 THB ($238-$280 USD) | 12,000-18,000 THB ($336-$504 USD) | Koh Tao is still the clear winner for certs. Phi Phi, Koh Lanta, and Phuket all charge significantly more | | Advanced Open Water (2 days) | 8,000-9,500 THB ($224-$266 USD) | 10,000-15,000 THB ($280-$420 USD) | Worth getting on Koh Tao before moving on to advanced sites | | Rescue Diver (3-4 days) | 9,000-11,000 THB ($252-$308 USD) | 12,000-18,000 THB ($336-$504 USD) | Less common to do outside Koh Tao | | Divemaster (6-8 weeks) | 25,000-35,000 THB ($700-$980 USD) | 40,000-60,000 THB ($1,120-$1,680 USD) | Koh Tao still dominates for professional courses |

Strategy: Get your certifications on Koh Tao (nobody is cheaper), then take those cards to the actually impressive dive sites. This is what experienced divers in Thailand do.

Fun Dive Pricing (2026)

| Location | Single Fun Dive | 2-Dive Day Trip | 10-Dive Package | |----------|----------------|-----------------|-----------------| | Koh Tao | 1,000-1,200 THB ($28-$34 USD) | 1,800-2,400 THB ($50-$67 USD) | 8,000-10,000 THB ($224-$280 USD) | | Koh Phi Phi | 1,500-2,500 THB ($42-$70 USD) | 3,000-4,500 THB ($84-$126 USD) | 12,000-18,000 THB ($336-$504 USD) | | Koh Lanta | 1,500-2,200 THB ($42-$62 USD) | 2,800-4,200 THB ($78-$118 USD) | 11,000-16,000 THB ($308-$448 USD) | | Koh Lipe | 1,400-2,000 THB ($39-$56 USD) | 2,800-4,500 THB ($78-$126 USD) | 11,000-16,000 THB ($308-$448 USD) | | Phuket | 2,000-3,500 THB ($56-$98 USD) | 4,000-6,500 THB ($112-$182 USD) | 16,000-25,000 THB ($448-$700 USD) | | Koh Chang | 1,500-2,500 THB ($42-$70 USD) | 3,000-4,000 THB ($84-$112 USD) | 12,000-18,000 THB ($336-$504 USD) |

The price jump from Koh Tao is real — expect to pay 50-100% more per dive at most other locations. But you are also paying for dramatically better conditions, healthier reefs, and encounters with marine life that simply does not exist around Koh Tao.

Use our budget calculator to work out your total Thailand trip costs including diving.

Seasonal Windows: When to Dive Where

Getting the season wrong is the single most common mistake divers make in Thailand. Showing up to the Similan Islands in July is like booking a ski trip in August — the infrastructure literally is not there.

Andaman Sea Sites (West Coast)

Open: Mid-October to Mid-May

| Month | Conditions | Notes | |-------|-----------|-------| | October (late) | Opening season. Some sites still rough. | Liveaboards start running mid-month. Deals available. | | November | Good. Visibility improving. | Occasional storms early month. | | December-February | Peak season. 25-40m visibility. | Busiest period. Book liveaboards months ahead. | | March-April | Peak whale shark season at Richelieu. | Best overall month for big encounters. | | May (early) | Closing season. Conditions declining. | Last chance before monsoon shutdown. Discounts on liveaboards. | | June-September | CLOSED. Monsoon. Dangerous seas. | Do not plan Andaman diving in these months. |

Gulf of Thailand Sites (East Coast)

Open: Year-round (with caveats)

| Month | Conditions | Notes | |-------|-----------|-------| | January-February | Decent. Post-monsoon clearing. | Visibility rebuilding after November-December storms. | | March-June | Best period. Calm seas, good visibility. | Whale shark season at Sail Rock and Chumphon Pinnacle. | | July-September | Good. Warm water. Some swells. | The Gulf is diveable when the Andaman is closed. | | October-December | Variable. Monsoon weather. | Gulf monsoon is less severe than Andaman but still brings rough days. November is typically worst. |

Planning tip: The dream Thailand dive trip hits both coasts. Arrive in November, dive the Andaman side (Similans, Richelieu, Hin Daeng) through April, then cross to the Gulf (Sail Rock, Chumphon Pinnacle) for May through September. Or in reverse if your timing starts in the Gulf season.

Safety: Staying Alive While Diving in Thailand

Thailand's dive industry is the largest in Southeast Asia, and the vast majority of operations are professional and safe. But it is also a loosely regulated industry in a developing country, and not all operators maintain the same standards. A few things to take seriously.

Get DAN Insurance

Divers Alert Network (DAN) insurance is the single most important thing you can buy before diving in Thailand beyond recreational depths. A hyperbaric chamber treatment for decompression sickness costs 50,000-300,000 THB ($1,400-$8,400 USD) in Thailand. DAN annual membership with dive accident insurance costs roughly $35-75 USD per year.

Thailand has hyperbaric chambers in:

Bangkok: Multiple hospitals
Phuket: Phuket Hyperbaric Services (Vachira Hospital)
Koh Samui: Bangkok Hospital Samui
Hat Yai: Hatyai Hospital

If you are diving at Hin Daeng (60+ meters wall), Chumphon Pinnacle (40 meters), or any deep site, the nearest chamber could be hours away by boat and then road. DAN insurance covers emergency evacuation and chamber costs. Get it.

Choosing a Dive Operator

Not all dive shops in Thailand are created equal. Koh Tao alone has over 50 operators, and quality ranges from excellent to genuinely dangerous. Here is what to check:

Green flags:

Equipment is well-maintained and recently serviced (ask when BCDs and regulators were last serviced — should be within 6 months)
Divemasters carry proper safety equipment (surface marker buoy, emergency oxygen, first aid)
Reasonable group sizes (4-6 divers per divemaster, not 8-10)
Thorough briefings that cover emergency procedures, not just "follow me"
They ask about your experience level and certification before booking

Red flags:

Pushing you to dive beyond your certification level
Equipment that looks battered, taped together, or mismatched
No safety oxygen on the boat
No briefing or a "briefing" that lasts 30 seconds
Massive group sizes (8+ divers per guide)
Pressure to skip safety stops or ascend faster

Price is not always the indicator you think. The cheapest operator on Koh Tao might have excellent safety standards, while an expensive Phuket resort operator might cut corners on group sizes. Research individual shops by name on dive forums and review sites.

Decompression Safety

Never fly within 18-24 hours of diving. This is not a guideline. This is the minimum safe surface interval before altitude exposure. Plan your last dive day accordingly.
Stay hydrated. Dehydration increases decompression sickness risk. Drink water before and between dives, especially in Thailand's heat.
Respect your computer. If your dive computer says you are approaching no-decompression limits, ascend. Do not follow a divemaster deeper if your computer disagrees.
Do a safety stop on every dive. Three minutes at five meters. Non-negotiable.
No alcohol before diving. This should be obvious, but on Koh Phangan during Full Moon Party week, it apparently is not. Alcohol dehydrates you, impairs judgment, and increases decompression sickness risk.

Nitrox Considerations

Enriched Air Nitrox (EAN32 or EAN36) extends your no-decompression limits, meaning more time at depth before you need to ascend. For multi-dive days on a liveaboard — where you might do 4 dives in a single day — nitrox is a significant safety and comfort advantage.

Most Similan liveaboards offer nitrox for 2,000-3,500 THB ($56-$98 USD) extra for the entire trip. The PADI Enriched Air Diver course takes about 3 hours (classroom only, no pool or open water dives) and costs 3,000-5,000 THB ($84-$140 USD). Worth getting before your liveaboard if you are doing 10+ dives.

Budget Diving Beyond Koh Tao: It Does Not Have to Break the Bank

Koh Tao has spoiled backpackers into thinking diving should cost $30 per dive everywhere. It does not. But there are legitimate ways to keep costs reasonable even at Thailand's premium dive sites.

Strategy 1: Get Certified Cheap, Dive Expensive

Do your Open Water and Advanced Open Water on Koh Tao. You will save 5,000-10,000 THB ($140-$280 USD) versus getting certified elsewhere. Then take your cards to the sites that actually deserve them.

Strategy 2: Book Multi-Dive Packages

Almost every dive shop in Thailand offers package discounts. Buying a 10-dive package on Koh Lanta saves 15-25% compared to paying per dive. If you are spending a week somewhere, always ask about packages.

Strategy 3: Shoulder Season Liveaboards

Similan liveaboards in late October and early May (the shoulder weeks when the park has just opened or is about to close) run discounts of 20-40% off peak season prices. The diving is still excellent — you might miss the peak whale shark window, but the visibility is often comparable.

Strategy 4: Bring Your Own Equipment

Rental gear adds 300-800 THB ($8-$22 USD) per dive at most locations. If you dive regularly, owning your own mask, fins, and wetsuit pays for itself within a few weeks of diving. BCD and regulator are harder to travel with, but your own mask and fins make a real difference in comfort and eliminate the biggest rental costs.

Strategy 5: Dive Koh Lipe Instead of the Similans

If the Similan liveaboard price tag (15,000-35,000 THB) is out of reach, Koh Lipe offers Andaman Sea quality at day-trip prices. The reefs are arguably healthier than the Similans (less traffic), and two-dive day trips run under 4,500 THB. The tradeoff is that you will not see Richelieu Rock or the deepest Similan sites, but the overall reef experience is outstanding.

Strategy 6: Work for Dives

Many dive shops on Koh Tao, Koh Lanta, and Koh Phi Phi offer free diving in exchange for work. The typical deal is 4-6 hours of daily work (cleaning tanks, manning the shop, helping on boats) in exchange for accommodation and 1-2 free dives per day. This is how a lot of long-term backpackers sustain their diving habit. The formal version is doing your PADI Divemaster internship, which often includes free accommodation, free diving, and a professional certification.

Sample Budget: 2-Week Dive Trip

Here is what a realistic 2-week dive-focused Thailand trip costs in 2026 for a budget-conscious diver:

| Expense | THB | USD | |---------|-----|-----| | Advanced OW on Koh Tao (2 days) | 8,500 | $238 | | 4 fun dives on Koh Tao | 4,000 | $112 | | 3-day Similan liveaboard | 18,000 | $504 | | 4 fun dives Koh Phi Phi or Koh Lanta | 6,000 | $168 | | Ferries and transport between islands | 4,500 | $126 | | Hostel accommodation (12 nights at 400 THB/night) | 4,800 | $134 | | Food (12 days at 500 THB/day) | 6,000 | $168 | | DAN insurance (annual) | 2,500 | $70 | | Total | 54,300 | $1,520 |

That is roughly $109 per day for two weeks of diving across Thailand's best sites, including a Similan liveaboard. Not backpacker-cheap, but this is a legitimate dive trip that covers serious ground. Cut the liveaboard and the budget drops to around $1,000 for two weeks.

Building a Dive Itinerary: Suggested Routes

The Gulf Loop (2 Weeks, Budget-Friendly)

Best for: Divers who want volume at low cost, year-round travel

Koh Tao (5 days): Get Advanced OW certified. Dive Chumphon Pinnacle and Sail Rock.
Koh Phangan (3 days): Sail Rock day trips (different angle). Mix dive days with beach days.
Koh Samui (2 days): Ang Thong Marine Park snorkeling day trip. Fly out.

Estimated dive cost: 15,000-20,000 THB ($420-$560 USD) for 10-12 dives

The Andaman Circuit (3 Weeks, Premium)

Best for: Experienced divers, November through April only

Khao Lak (4 days): 3-night Similan + Richelieu liveaboard.
Koh Phi Phi (4 days): Day trips to Shark Point, Anemone Reef, King Cruiser.
Koh Lanta (4 days): Day trips to Hin Daeng, Hin Muang. Rest days between deep dives.
Koh Lipe (5 days): Tarutao National Park diving. Chill island pace.

Estimated dive cost: 40,000-60,000 THB ($1,120-$1,680 USD) for 18-24 dives

The Complete Thailand Dive Tour (4-6 Weeks)

Best for: The obsessed. Start in November, end in May.

Combine both loops above. Start on the Andaman coast when it opens in October/November, work your way south to Koh Lipe, then cross to the Gulf side (ferry from Koh Lipe to Koh Lanta, then overland to Surat Thani, ferry to Koh Tao). Finish the trip with Gulf diving during the Andaman's late-season wind-down.

Check the island ferry guide for cross-coast transfer options.

Gear to Bring (And What to Rent)

You do not need to bring a full dive setup to Thailand. But a few personal items make a significant difference.

Bring from home:

Mask: The single most important piece of personal dive gear. A well-fitting mask you know does not leak beats any rental. 800-2,500 THB ($22-$70 USD) to buy.
Dive computer: If you own one, bring it. Rental computers are often basic and may not match your dive profile preferences. Entry-level computers like the Aqualung i100 start around 8,000 THB ($224 USD).
Reef-safe sunscreen: Oxybenzone-based sunscreen kills coral. Bring mineral-based reef-safe sunscreen from home — it is harder to find and more expensive in Thailand.
Rashguard or thin wetsuit (1-3mm): Thai waters are 28-30 degrees Celsius on the surface, but you still cool down on multi-dive days and 3mm wetsuits are the most commonly rented size. Having your own guarantees fit.

Rent in Thailand:

BCD, regulator, fins, weights — standard rental everywhere
Wetsuit (if you did not bring one)
Underwater torch (included on night dives, rentable otherwise)
Underwater camera housings (some shops rent GoPro setups)

Common Mistakes Divers Make in Thailand

Diving during monsoon on the wrong coast. Every year, divers show up to Khao Lak in July wondering why all the liveaboards are dry-docked. Check the season chart above. Mark it in your calendar. Plan around it.

Skipping Advanced Open Water. The best sites in Thailand — Richelieu Rock, Chumphon Pinnacle, Hin Daeng, Sail Rock chimney — are all deep dives that require or strongly recommend Advanced OW. Getting the certification takes two days and costs under 10,000 THB on Koh Tao. There is no reason to skip it if you are serious about diving Thailand.

Not buying DAN insurance. A hyperbaric chamber session costs more than your entire dive trip. DAN insurance costs less than two dives on Koh Tao. The math is obvious.

Choosing operators on price alone. The 200 THB you save on a cheap operator is irrelevant if their equipment is poorly maintained or their divemaster is managing 10 people at once. Read reviews. Ask questions. A few hundred baht buys significantly better safety.

Diving after partying. Koh Phangan Full Moon Party followed by a 7am dive boat is a real thing people attempt. Alcohol impairs judgment, dehydrates you, and increases decompression sickness risk. Take a rest day between the party and the dive.

Not allowing time before flying. The 18-24 hour no-fly rule after diving is not optional. If you are doing multiple deep dives on a liveaboard, extend that to a full 24 hours. Plan your last dive day at least one full day before your flight home.

Final Thought

Koh Tao gave you the card. It taught you to clear a mask, equalize your ears, and breathe underwater. That is genuinely valuable, and there is nothing wrong with Koh Tao for what it is.

But Thailand's diving does not peak on Sairee Beach. It peaks on a predawn liveaboard descent at Christmas Point when the Similan granite boulders materialize from the blue. It peaks inside the chimney at Sail Rock as light pours in from above and a school of batfish spirals past you. It peaks at Richelieu Rock when a whale shark glides out of the visibility and you forget everything you were thinking about.

Get the cert on Koh Tao. Then go somewhere that earns it.

Related Guides

How to Get to Koh Tao — Every route from Bangkok, Chiang Mai, and beyond
Thailand Island Ferry Guide — Routes, prices, and schedules for both coasts
Thailand Islands Itinerary — Gulf vs Andaman complete planning guide
Beach Safety in Thailand — Currents, jellyfish, and ocean safety
Budget Calculator — Build your custom Thailand trip budget