Regions
Thailand's Islands: Choose Your Coast Before Choosing Your Island
First, choose the sea; then, choose the island. That’s the opposite order of what everyone else does, and it’s the one that keeps you from ending up in the wrong place at the wrong time.
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Thailand has more than a thousand islands, and most comparison guides ask you to choose between them right away. That’s the wrong first question.The right one is: which sea? The country has two—the Andaman Sea to the west and the Gulf of Thailand to the east—and they don’t have the same tourist season. A beautiful island visited at the wrong time of year will be rainy.
Once you've chosen a sea, the rest is easy: every coastline offers an easily accessible island with an airport, a party island, and one or two quiet islands an hour away by boat. Here's how to decide, in this order.
The Two Seas and Their Opposing Seasons
| Andaman Sea, to the west | Gulf of Thailand, to the east | |
|---|---|---|
| Best period | from November through April | from January through September |
| Months to Avoid | from May through October | November, the rainiest month |
| The Landscape | vertical limestone peaks, cliffs, emerald-green water | rolling hills, coconut palms, long sandy beaches |
| Major Islands | Phuket, Phi Phi, Koh Lanta, Railay, Similan | Koh Samui, Koh Phangan, Koh Tao |
| On-site airport | Phuket, Krabi on the mainland | Koh Samui |
November is worth noting because it can throw a wrench into many trips: it’s the rainiest month in the Gulf and one of the best months along the Andaman Coast. Two islands 300 kilometers apart, two completely different trips. The month-by-month breakdown is on the Thailand weather page.
The Andaman Coast, to the west
Phuket, the gateway
The country's largest island, connected to the mainland by a bridge and home to an international airport. It's the most convenient point of entry along the entire west coast—and also the most developed: you can find everything there, including the very things you came to escape. Many travelers land there and leave the next day for a quieter destination.
Krabi and its islands: a postcard-perfect landscape
On the mainland, about a three-hour drive from Phuket, Krabi Province offers some of the coast’s most beautiful scenery: Railay, a peninsula accessible only by boat, with its vertical cliffs and rock climbers, and the departure points for the Phi Phi Islands and Koh Lanta, which is longer, flatter, and much quieter.
The Gulf of Thailand, to the east
Koh Samui, the easiest
An airport, roads, hospitals, and an established French-speaking community. This is the island you can arrive at without making any plans, and from which you can reach the other two by boat. The south and east of the island are significantly quieter than the north.
Koh Phangan: The Party and Everything Else
Known for the Full Moon Party, which takes place on just one beach for one night each month. The rest of the island is much quieter than people realize, and its northern part has been home to a long-term resident population for years.
Koh Tao, Diving
The smallest of the three, and one of the cheapest places in the world to get your first-level diving certification. That's what gives it its reputation and its atmosphere: many people come here for three days and end up staying for three weeks.
Make Your Choice in Three Questions
| What you're looking for | Andaman | Gulf |
|---|---|---|
| Spectacular landscapes | Railay, Phi Phi | less pronounced |
| Take it easy | Koh Lanta | south of Koh Samui, north of Koh Phangan |
| Diving | Similan, a day trip | Koh Tao |
| Party Time | Phuket, Phi Phi | Koh Phangan |
| Arriving without making any plans | Phuket | Koh Samui |
What You Need to Know Before Booking
Don't try to visit both coasts on a short trip. Traveling from one to the other takes a full day of travel or requires a domestic flight. If you have two weeks, it's better to choose one coast and explore it thoroughly than to cross the country just to check both off your list.
Boat schedules are subject to weather conditions. During the off-season, services may be suspended without notice. It’s not overly cautious to allow for an extra day before an international flight from an island.
ATMs are rare on small islands, and not all merchants accept credit cards. Full details are available on the "Travel Credit Cards" page ( coming soon).
In summary
First, choose the sea, then the island. The Andaman Sea from November to April for the limestone cliffs of Krabi and Railay; the Gulf of Thailand from January to September for Koh Samui, Koh Phangan, and diving in Koh Tao. November marks a clear dividing line between the two. Once you’ve chosen a coast, each sea offers the same variety: an easily accessible island with an airport, a party island, and a quiet island an hour away by boat. The complete map of the regions is on the Thailand map page.
What is the most beautiful island in Thailand?
It depends on the sea and the season. Along the Andaman coast, the islands of Krabi Province offer the most spectacular scenery, with their limestone peaks. In the Gulf, Koh Tao is the most popular among divers, and Koh Samui is the easiest to reach thanks to its airport.
Which island should you choose for your first trip to Thailand?
Koh Samui or Phuket, because they have airports and everything is well organized there. They also serve as starting points for trips to quieter islands, an hour or two away by boat.
Which ocean should you choose depending on the month?
The Andaman Sea, to the west, from November through April. The Gulf of Thailand, to the east, from January through September. November is the worst month for the Gulf and one of the best for the Andaman: it’s this difference that should be the deciding factor, rather than the photo.
How long does it take to get from one island to another?
Allow one to three hours by boat between neighboring islands in the same sea. Traveling from one sea to another takes a full day, or a domestic flight costing €30 to €60, which is often the best option.
Which island is best for diving in Thailand?
Koh Tao, in the Gulf, is one of the cheapest places in the world to get your first-level certification. On the Andaman side, the Similan Islands offer more spectacular dive sites, accessible on day trips from Phuket or Khao Lak.
Do you need to reserve boats in advance?
During peak season and for long-distance routes, yes. On short trips between neighboring islands, departures are frequent and tickets can be purchased on the spot without any trouble.