Scuba Diving in Thailand

Diving in Thailand splits almost neatly into two coasts and two seasons, and that's the whole story behind why it's been a top-tier dive country for thirty years. The Andaman Sea on the west gives you granite-pinnacle dives in the Similan Islands, whale sharks at Richelieu Rock, and Thailand's biggest vertical wall at Hin Daeng. The Gulf of Thailand on the east gives you Sail Rock's chimney swim-through and the world's cert capital on Koh Tao. Beyond the diving, Thailand is also home to glittering temple complexes, jungle-clad limestone karsts, and one of the most loved food cultures on the planet.

Why dive in Thailand?

• Two coasts, two seasons — The Andaman runs October to May with calm seas, 20 – 30 m (65 – 100 ft) visibility, and granite-pinnacle topography; the Gulf runs May to September with shallower, calmer training-friendly reefs and the Sail Rock chimney.
• Thailand's most reliable whale shark sites — Richelieu Rock and Hin Daeng on the Andaman side from February to April, with a second window at Sail Rock from March through September.
• The world's cert capital — Koh Tao trains more new divers each year than anywhere else, with shallow, calm, year-round fun diving at the cheapest rates in the country.
• Thailand's tallest submerged pinnacle wall — Hin Daeng & Hin Muang off Koh Lanta, wrapped in pink and purple soft coral and drawing oceanic mantas.
• Topside that earns the extra days — Khao Sok jungle, Phang Nga karsts, Phuket Old Town shophouses, and the most loved food culture on the planet.

Where to dive in Thailand

Where to dive in Thailand depends on which coast is in season and what you want underwater, so the regions below cover the trips divers actually book.

Similan Islands

Similan Islands

The Similan Islands are the crown of Thai diving, a chain of nine granite islands in the north Andaman with hard-coral gardens on the east side and house-sized boulder dives on the west. If you only do one trip in Thailand, this is the one, and the park is only open mid-October to mid-May.

Surin Islands & Richelieu Rock

Surin Islands & Richelieu Rock

Head north of the Similans for the Surin Islands and Richelieu Rock, Thailand's most famous pinnacle and the country's most reliable whale shark site between February and April, when plankton blooms pull the big fish in.

Hin Daeng & Hin Muang

Hin Daeng & Hin Muang

If you like deep pinnacle dives with the chance of mantas and the occasional whale shark, head to Hin Daeng & Hin Muang off Koh Lanta, where Thailand's biggest vertical wall is wrapped in pink and purple soft coral.

Phi Phi Islands

Phi Phi Islands

Looking for limestone walls and easy day-boat diving with green turtles, blacktip reef sharks, and leopard sharks, Phi Phi holds ten dive sites that reopened in 2025 after a year-long bleaching closure, all reachable on day trips from Phuket or Krabi.

Phuket

Phuket

Phuket is the country's busiest dive gateway, with quick boat hops to Shark Point, Anemone Reef, and the Racha Islands, useful for shaking off jet lag with a couple of warm-up dives before a liveaboard or for a relaxed week of day boats.

Koh Lipe

Koh Lipe

Koh Lipe sits at the southern tip of the Andaman inside Tarutao National Marine Park, with colorful soft-coral pinnacles and one serious offshore seamount at 8 Mile Rock that pulls in whale sharks and manta rays from March through September.

Koh Tao

Koh Tao

If you're learning to dive or you want shallow, calm, year-round fun diving at the cheapest rates in the country, Koh Tao is the cert capital of the world and trains more new divers each year than anywhere else.

Koh Samui

Koh Samui

Koh Samui is the comfortable Gulf launchpad for Sail Rock and Ang Thong day trips, with an international airport on the island and resort-grade logistics that suit divers traveling with non-divers.

Koh Phangan & Sail Rock

Koh Phangan is the launchpad for Sail Rock, the Gulf of Thailand's best dive site, famous for a vertical chimney swim-through that rises through the pinnacle and the whale sharks that show up reliably from March through September.

Best time to dive Thailand

The best time to dive Thailand depends on which coast you're heading to, because the monsoon swings between the two. The Andaman side runs from mid-October to mid-May with calm seas, 20 – 30 m (65 – 100 ft) visibility, and water around 28 – 30 °C (82 – 86 °F); the Gulf is best from May to September. The Similan and Surin marine parks are closed every year from May 16 to October 14 to let the reefs rest.

Thailand culture — other reasons to go

Thailand makes the case for a dive trip with non-diving days baked in. From Khao Lak, the main liveaboard departure port for the Similans, you're 90 minutes from Khao Sok National Park, where floating bungalows on Cheow Lan Lake wake up to the call of gibbons. Phang Nga Bay's limestone karsts are paddleable in a sea kayak straight out of Phuket. Phuket Old Town's a Sino-Portuguese walking grid full of dim-sum shops and weekend markets, with the Big Buddha looking out over the south of the island. Down on the Gulf side, Koh Phangan and Koh Tao have trail networks running through coconut groves and viewpoints worth a half-day off the boat, and the Wat Plai Laem temple complex on neighboring Koh Samui is an easy ferry hop. The food is the other half of the trip: every dive town has a night market within walking distance of the dive shops, and the southern Andaman coast is one of the best places in the country to eat seafood the day it was caught.

• Khao Sok National Park & Cheow Lan Lake — Floating bungalows, kayaking, and early-morning gibbon spotting, about 90 minutes from Khao Lak
• Phang Nga Bay — Limestone karst paddling and the islands made famous by the Bond films, easy half-day from Phuket
• Phuket Old Town — Sino-Portuguese shophouses, the Sunday Walking Street market, and the easiest food crawl in the country
• Big Buddha of Phuket — Marble statue with panoramic views over the south coast, perfect surface-interval afternoon
• Wat Plai Laem (Koh Samui) — Multi-armed Guanyin statue and a quick temple loop, ferry-friendly from Koh Phangan
• Bang Niang Night Market (Khao Lak) — Open Thursday, Saturday, Monday, and Wednesday with the best cheap pad krapow on the Andaman coast

Marine life highlights

The top marine life to see in Thailand sits at the western edge of the Coral Triangle's influence, with the Andaman Sea offering pelagic action and the Gulf serving up a calmer, macro-friendly counterpoint. The country is best known for seasonal whale sharks and manta rays in the north Andaman, but reef sharks, turtles, and big schools of trevally and barracuda are reliable year-round across both coasts.

• Whale sharks (Rhincodon typus) — February to April at Richelieu Rock and Hin Daeng, with a second window from March to September at Sail Rock on the Gulf side
• Manta rays (Mobula alfredi) — Cleaning and feeding at Koh Bon and Koh Tachai in the Similan park, peaking January through April
• Leopard sharks / zebra sharks (Stegostoma tigrinum) — Year-round on the Andaman side, especially at Shark Point near Phuket and Hin Daeng
• Blacktip reef sharks (Carcharhinus melanopterus) — Back at Maya Bay since the reopening, plus reliably patrolling the shallows around Phi Phi and the Similans
• Green and hawksbill turtles — Common at Phi Phi, the Similans, and Koh Tao, often resting on coral ledges in 5 – 15 m (15 – 50 ft)
• Seahorses, nudibranchs, and ghost pipefish — Macro standouts on Koh Tao and the bay dives around Phuket, especially the dark-bottom muck sites
• Bull sharks (Carcharhinus leucas) — Occasional visitors to Sail Rock in the Gulf, mostly between April and October

Conservation

Marine conservation in Thailand is in the middle of an aggressive course-correction on reef protection, and divers should pay attention because the rules have shifted fast. Roughly 10% of the country's coastal and marine areas now sit inside marine protected areas, and about 15.7% of the Exclusive Economic Zone is managed under ecosystem-based approaches, with hundreds of new sites added to global conservation databases in the last two years. The 2024 mass bleaching event affected 152 reef sites across 21 marine parks (nine in the Gulf, twelve in the Andaman) and pushed the Department of National Parks to temporarily close popular dive areas including ten around Phi Phi, which reopened in 2025 after monitoring. New rules ban reef-harming sunscreen with fines up to 100,000 baht, and from October 2025 the Similan, Surin, and Phi Phi parks shifted to a pre-booked e-ticket system to cap visitor numbers. Local momentum is real too: dive operators on Koh Tao like New Heaven Reef Conservation, Black Turtle Dive, and Big Blue Conservation run citizen-science Reef Watch surveys and DMCR-authorized coral restoration programs you can join as a recreational diver.

How you can help: Choose operators that fund this work, leave the chemical sunscreen at home, and keep your fins clear of the coral. Read more about Divearoo's Conservation First policies.

Practical information

Dive prices

Expect to pay around 3,200 – 4,500 THB (about USD 90 – 130) for a 2-tank day boat trip with full gear in most parts of Thailand, with Koh Tao on the cheaper end and Similan day trips out of Khao Lak on the higher end. Liveaboard rates run roughly 4,400 THB per day for budget boats up to 23,500 THB for the high-end operators (USD 130 – 700/day), with most mid-range Similan/Surin trips landing around 6,000 – 9,000 THB per day. Cost scale across the country: $$.

Visa information

Thailand offers visa-free entry to passport holders from 93 countries including the US, UK, all EU member states, Canada, and Australia, currently for up to 60 days, with two paid extensions available (about 1,900 THB each) for a maximum of roughly 97 days per entry. Some passports get a 15-day visa on arrival instead, and the Thailand E-Visa has been available worldwide since January 2025. Every foreign visitor must complete the free Thailand Digital Arrival Card (TDAC) online within 72 hours of arrival.

Marine park entry fees are charged on top of dive trips and are typically paid in cash to the operator: 500 THB per park for the Similan Islands and Surin Islands (so 1,000 THB combined on a liveaboard that hits both), 400 THB for Phi Phi, and around 300 THB at Ang Thong. Many marine parks moved to a pre-booked e-ticket system starting October 2025, so confirm the booking method with your operator before you fly.