# Scuba Diving Thailand: Where to Dive & What to Expect
Thailand is where half the divers I know got certified. There's a reason for that. Twenty-five-dollar dives. Warm water. Whale sharks if you time it right. And pad thai between surface intervals.
I've dived both coasts across four trips. The Andaman side and the Gulf side are basically different countries underwater. Here's the breakdown.
Top Dive Regions
Koh Tao — The Cheapest PADI Certs in the World
Koh Tao is a factory. I mean that in a mostly positive way. The island has more PADI dive shops per square kilometer than anywhere on Earth. Open Water certification runs $250–$350, which is roughly half what you'd pay in the Caribbean and a third of US prices.
The diving itself is decent, not spectacular. Chumphon Pinnacle offers occasional whale sharks. Sail Rock (technically between Koh Tao and Koh Phangan) is genuinely excellent — a vertical chimney you can swim through with barracuda schooling overhead.
If you're getting certified for the first time, it's hard to beat the value. Just pick a shop with small class sizes. The difference between a 2:1 and an 8:1 student-to-instructor ratio is everything.
Similan Islands — Thailand's Best Diving
This is the real deal. The Similans are a national park in the Andaman Sea, accessible from Khao Lak. The coral is healthy. Visibility routinely hits 30 meters. Manta rays are common at Koh Bon.
Liveaboards are the best way to dive here — 3-day trips run $400–$700 and cover sites you can't reach on day boats. I've done both. The liveaboard is worth it.
The park closes May through October. Non-negotiable.
Koh Phi Phi — Easy Access from Phuket
Phi Phi gets a bad rap from divers because it's touristy. Fair. But the diving at Hin Daeng and Hin Muang (south of Phi Phi) is legitimately world-class. These are deep pinnacles with mantas, whale sharks, and soft coral walls.
The sites closer to Phi Phi itself are fine for newer divers. Leopard sharks at Shark Point are reliable.
Richelieu Rock — Whale Sharks
If you dive one site in Thailand, make it Richelieu Rock. It's a horseshoe-shaped pinnacle absolutely covered in soft coral, and it's the country's best whale shark site. February through April gives you the best odds.
It's only accessible via liveaboard from the Similans route. Worth the trip.
Best Time to Dive
Thailand has two coasts with opposite monsoon seasons:
- Andaman Sea (west coast): November through April. This covers the Similans, Phi Phi, Richelieu Rock, and Phuket. The park literally closes during monsoon.
- Gulf of Thailand (east coast): May through October is the calm season. Koh Tao, Koh Phangan, Koh Samui. You can dive year-round, but visibility peaks in these months.
Typical Costs
Thailand diving is the cheapest quality diving in the world:
| Item | Cost | |------|------| | Fun dive (1 tank) | $25–$40 | | Day trip (2 tanks) | $60–$80 | | Open Water certification | $250–$350 | | Advanced OW | $200–$300 | | Similan liveaboard (3 days) | $400–$700 | | Equipment rental (full kit) | $15–$25/day |
Compare that to $80–$150 per dive in the Caribbean. The math is obvious.
Getting Certified in Thailand
A huge percentage of the world's divers earn their Open Water card in Thailand. The combination of warm water, low prices, and social atmosphere makes it the default choice for backpackers and budget travelers.
A few things to know:
- Course takes 3–4 days. Two days of theory and confined water, two days of open water dives.
- Shop quality varies wildly. Read recent reviews. Ask about class sizes. Small groups matter more than price differences.
- Your certification is valid worldwide. PADI and SSI cards earned in Thailand work everywhere. Same curriculum, same standards.
Monsoon Seasons by Coast
People get confused by this, so let me be specific:
Southwest Monsoon (May–October): Hits the Andaman coast. Heavy rain, big swells. Similan park closed. Phuket diving limited. But the Gulf coast is calm and clear.
Northeast Monsoon (November–February): Hits the Gulf coast. Koh Tao gets choppier. But the Andaman coast is in peak season. December through February is prime Similans time.
March–April: Both coasts are generally good. This is the sweet spot if you want to dive both sides in one trip.
Visa Considerations
Most nationalities get 30 days visa-free on arrival (recently extended from the old 15-day stamp for some countries — check current rules). That's plenty for a dive trip.
If you're doing a longer stay — getting certified, diving both coasts, island-hopping — you can extend once for 30 more days at an immigration office for 1,900 baht (~$55).
Digital nomad visa options are expanding, but for a standard dive holiday, the visa-free entry or tourist visa covers it.
Bottom Line
Thailand isn't the best diving in the world. It's the best value diving in the world. The Similans and Richelieu Rock genuinely compete with top-tier destinations, and you're paying a fraction of what the same experience costs elsewhere.
Get certified here. Dive here. Eat pad thai between dives. The math works.
I'm Chad. Chemist. Diver. I've spent about $3,000 total on four Thailand dive trips. That's what two weeks of diving costs in some Caribbean destinations.