Dive Trip Thailand: Where, When & How to Plan

Featured image: Inchka, CC BY 2.0, via Flickr.

Quick answer: coast, season and format by diver type

Match your travel month to a coast before anything else. November to April points you to the Andaman Sea. May to September points you to Koh Tao in the Gulf. Format comes next, and it depends on your logbook more than your budget.

Andaman Sea or Gulf of Thailand?

The two coasts have close to opposite seasons. Andaman diving is best from November to April, with calm seas and the clearest water. June to October is monsoon there, with choppy conditions and lower visibility. Gulf diving peaks from May to September. Koh Tao reports its clearest water in July and August. October to February brings rougher seas on that side, although many dive schools keep running on the good days. Typical visibility reaches about 30 m, and water stays between 25°C and 30°C all year. Liveaboards mostly stop in the Andaman monsoon, but the southern Andaman can stay diveable in July. Day boats from the Phuket area are the usual way to use that window. Park closures vary by year, so check the national parks department before booking.

Best Andaman dive areas

The Andaman holds Thailand's biggest names. The Andaman Sea diving guide covers each area in depth. Here is how they fit a trip.

• Similan Islands: a marine park of eleven granite islands with walls, swim-throughs and boulders. There is no overnight stay on the islands, so most divers come by liveaboard.
• Surin Islands: about 100 km north of the Similans, and 80% of the park is ocean. Richelieu Rock sits about 10 km southwest of Ko Surin and suits divers comfortable with current.
• Phuket: day trips to Shark Point, Anemone Reef, Racha Noi and Racha Yai. King Cruiser Wreck is a deep wreck dive, so see the wreck diving guide before booking it.
• Koh Phi Phi: over 20 dive sites, including Bida Nok and Bida Nai. Diving runs all year, with the best conditions from February to May.
• Koh Lanta: Koh Haa suits beginners, with the Cathedral cavern and the Chimney swim-throughs. Hin Daeng and Hin Muang are remote pinnacles for advanced divers.

Best Gulf dive areas

Koh Tao is the Gulf's dive hub, and it is only about 21 km² in size. It has roughly 25 dive sites, with reefs, ocean dives and pinnacles. Sail Rock is the famous one, with large barracuda schools and rock formations. Chumphon Pinnacle and White Rock, a night-dive favorite, are also on most boat lists. Whale sharks turn up at Sail Rock in some seasons, but sightings are never promised. Koh Samui has no dive sites of its own. Stay there if you like resorts, but expect day trips to Koh Tao's sites. For regional detail, read the Gulf of Thailand diving guide. Mainland alternatives are in the Chumphon Diving: Sites, Season, Costs & Pinnacle Guide and Hua Hin Diving: Day Trips, Seasons & Alternatives pages.

Dive center or liveaboard?

A dive center gives you a fixed bed, daily boats and courses. A liveaboard gives you remote sites, up to four dives a day and no daily transfers. Many resorts offer discounts on food and rooms to diving guests, so compare packages on the Thailand dive resorts page. Liveaboards often ask for logged dives, so read each boat's requirement before paying a deposit.

What a dive trip in Thailand costs

Prices and hours checked November 2026, from operator-published ranges. A two-dive fun day with gear rental runs about ฿4,100. Add a third dive and it rises to about ฿4,700. An Open Water plus Advanced course bundle costs around ฿17,450 or less on cheaper islands such as Koh Tao. A four-day liveaboard ranges from about ฿19,800 to about ฿50,000, depending on boat standard. Park fees, flights, insurance and sometimes gear rental are usually extra. Divers Alert Network sells dive accident cover, and remote sites make insurance worth pricing in. Our Thailand diving cost breakdown goes deeper.

Sample trip shapes for a Thailand dive trip

Treat these as frameworks and fit the days to your own sailing dates.

• Liveaboard week: fly into Phuket, board for a Similan and Surin route, and add day boats before or after.
• Learn-to-dive week: base on Koh Tao from May to September. Take an Open Water course, then add fun dives at Sail Rock.
• Split-coast trip: Andaman first in spring, then the Gulf later in the season if your dates reach May.
• Advanced add-on: ask about technical diving options only if you hold the training.

Getting there and around

Phuket is the usual gateway for Andaman trips, and Koh Tao is reached by ferry from the Gulf coast, including via Chumphon. Ferry times and fares change by season, so check current timetables with the operator before you book onward.

Diving responsibly in Thailand's marine parks

Do not touch coral, turtles or sharks. Wear reef-safe sunscreen and carry a surface marker buoy. Choose operators that run reef cleanups or coral surveys. Trained divers from PADI-affiliated centers set an Open Water depth limit of 18 m. Try Dive sessions are capped near 12 m. Pick a boat that respects both, and decline any dive beyond your certification. Check park rules with the national parks department before visiting a marine park.

Common mistakes to avoid

Most trip problems come from planning the wrong coast or underestimating extras.

• Booking the Gulf in Andaman season, or the reverse.
• Assuming Koh Samui has dive sites of its own.
• Booking a liveaboard without the logged dives it requires.
• Skipping park fees and transfers in your budget.
• Choosing Hin Daeng or Richelieu Rock as a first current dive.
• Expecting mantas or whale sharks on a fixed date. February to April gives the best odds in the Andaman, but nothing is guaranteed.

Where to go next

Compare sites in the best Thailand dive sites. Read the best diving in Thailand for ranked areas. Cave divers can start with the cave diving page. The Ranong diving guide covers a northern Andaman base.