Thailand’s islands are the stuff of screensavers, but they are not interchangeable, and picking the wrong coast for your dates is the classic first-timer mistake. The country’s beaches split across two very different seas, the Andaman to the west and the Gulf to the east, each with its own scenery, rhythm and, crucially, its own season. Here is how to choose the right one for your trip.
The two coasts in a nutshell
The Andaman coast, west of the mainland, is the dramatic one: sheer limestone karst cliffs rising straight out of jade water, the postcard scenery of Phi Phi, Krabi and Phang Nga Bay. It is generally at its best roughly November to April. The Gulf of Thailand, to the east, is gentler and often greener, with softer beaches, superb diving and a season that frequently runs January to August, sometimes staying dry when the Andaman is stormy. Get the season right and half the work of planning is done.
The Andaman side: Phuket, Krabi, Phi Phi
The Andaman coast is the busiest and best connected. Phuket is the big one, an island with an airport, every kind of hotel, buzzing nightlife and beaches for all tastes, and a fine base for boat trips. Krabi, across the bay, trades some of the polish for jaw-dropping scenery: the climbing cliffs of Railay, longtail boats, and easy hops to nearby islands. Phi Phi is the iconic day-trip and party island, home to Maya Bay, the cove the films made famous.
Maya Bay is worth a paragraph of its own, because it no longer works the way the photographs suggest. After years closed for reef recovery it reopened under strict national park rules: boats no longer land on the famous beach but pull in at Loh Samah on the back of the island, from where a short boardwalk brings you out onto the sand; swimming in the bay is not permitted, only wading; numbers on the beach and time on site are capped; and there is a national park entry fee of a few hundred baht per adult. The bay also closes completely for part of the year to let the reef rest, in recent seasons through August and September, while the wider Phi Phi boat trips keep running without the beach stop. Check the current fee, hours and closure dates with your operator before you book, since the park reviews them annually.
Choose the Andaman if you want the most dramatic scenery, the widest choice of flights and hotels, and you are travelling in the cool, dry months.
The Gulf side: Samui, Phangan, Tao
The Gulf trio sits close together and covers three moods. Koh Samui is the comfortable all-rounder: an airport, resorts, spas, family beaches and easy living. Koh Phangan, its neighbour, is famous for the monthly Full Moon Party but is also surprisingly serene away from the beach parties, with jungle, yoga retreats and quiet coves. Koh Tao is the diving capital, one of the cheapest and best places in the world to learn to scuba dive, ringed by clear, life-filled water.
Book a snorkel or dive day on the GulfKoh Tao and its reefs are among the world's best value underwaterChoose the Gulf if you want calmer beaches, world-class diving, that Full Moon energy, or you are travelling when the Andaman is wet.
How to actually choose
Start with your dates, not your Pinterest board. Travelling November to April? Lean Andaman. Travelling in the summer green season? The Gulf will likely give you better weather. Then match the vibe: dramatic cliffs and variety point west, gentle beaches and diving point east. And be realistic about travel time, since the coasts sit on opposite sides of the peninsula. Combining both on one trip is possible but eats a day of ferries and flights, so most people pick one coast and island-hop within it. Our best time guide and getting around guide fill in the logistics.
Getting there and hopping around
Most island trips run through Phuket, Krabi or Koh Samui airports, or by ferry from mainland piers like Surat Thani and Krabi town. Within each coast, frequent ferries and speedboats link the islands, so hopping is easy once you arrive. Book ferries a little ahead in high season, watch the last-boat times, and travel light, as many transfers involve wading a few steps onto a beach.
The short version
Two seas, two seasons, two very different holidays. The Andaman coast delivers the dramatic karst scenery and the most connections, best roughly November to April. The Gulf offers calmer beaches, brilliant diving and often better summer weather, frequently good January to August. Pick your coast by your dates first, then your vibe, hop within it rather than crossing back and forth, and you will get the island trip you actually came for.
