Thailand has hundreds of islands, but the practical map for a trip comes down to a few clusters, two coasts, and one fact that governs everything: the coasts have opposite seasons. Get the timing and the grouping right and island hopping here is straightforward; get them wrong and you spend a holiday watching rain bounce off a longtail boat. This is the planning overview — the routes, the ferries and the seasons — rather than a single fixed itinerary.
The two coasts and their opposite seasons
The Andaman coast in the west — Phuket, Krabi, Koh Phi Phi, Koh Lanta and far-south Koh Lipe — is at its best in the dry season from November to April, with calm, clear water ideal for snorkelling and diving. From around May to October the south-west monsoon brings rough seas, and some marine parks (the Similan and Surin Islands) close entirely.
The Gulf coast in the east — chiefly Koh Samui, Koh Phangan and Koh Tao — runs on a different clock. It stays good from roughly January to September and gets its heaviest rain and biggest swells from October to December. The practical upside is that there is usually decent island weather somewhere in Thailand year-round; you just follow it to the right coast.
Andaman cluster: Phuket, Phi Phi, Krabi, Lanta
The classic western chain links Phuket, Koh Phi Phi, the Krabi coast (Ao Nang and Railay) and Koh Lanta, with ferries running between all of them in high season. A common loop flies into Phuket, takes the ferry to Phi Phi for a night or two, continues to Krabi or Railay for limestone scenery and rock climbing, and finishes on the quieter, longer beaches of Koh Lanta. Day trips from any of these reach the smaller islands — Bamboo, Koh Hong, the Hong Islands — by longtail or speedboat.
Gulf cluster: Samui, Phangan, Tao
The eastern chain is tighter and easier. Frequent ferries connect Koh Samui, Koh Phangan and Koh Tao in under two hours each, so you can base on one and day-trip to the others, or move through all three. Samui has the airport and the resorts, Phangan the beaches and the Full Moon Party, and Koh Tao the cheap diving. Day trips from Samui or Phangan reach the cliffs and lagoons of the Ang Thong Marine Park.
Quieter alternatives: Lipe, Chang, Mak, Kood
For fewer crowds, two corners of the country deliver. Far south in the Andaman, tiny Koh Lipe sits in a marine park with clear water and walkable beaches, reached by speedboat from Pak Bara. In the east near the Cambodian border, the Trat islands — forested Koh Chang, low-key Koh Mak and the resort-quiet Koh Kood — form their own small chain, easiest in the November-to-April dry window and almost shut down in the wet season.
How the ferries actually work
Boats range from large car-and-passenger ferries to fast, bouncy speedboats and traditional longtails for short hops. In high season, book the popular routes a day or two ahead online — combined boat-and-bus tickets through booking platforms save juggling connections — while in low season you can usually turn up at the pier. Build in buffer time: ferries are weather-dependent and run reduced schedules in the monsoon, and the last boat of the day is earlier than you think.
Crossing between the coasts
There is no direct island-to-island ferry between the Andaman and the Gulf — they sit on opposite sides of the peninsula. Crossing means returning to the mainland and taking a bus or a short domestic flight, for example from Krabi or Phuket across to Surat Thani for the Gulf island piers. It is doable in a long day, but because it eats time, most two-week trips pick one coast and explore it properly rather than splitting the difference.
Frequently Asked Questions
Which Thai islands are best for island hopping?
It depends on the coast and season. On the Andaman side, chain Phuket, Koh Phi Phi, Krabi and Koh Lanta. On the Gulf side, link Koh Samui, Koh Phangan and Koh Tao. The far-south Koh Lipe and the eastern Koh Chang, Koh Mak and Koh Kood are quieter alternatives.
Can you island hop between the Andaman and the Gulf coasts easily?
Not quickly — they are on opposite sides of the peninsula with no direct island ferries between them. Crossing usually means a bus or a short domestic flight via the mainland (for example Krabi or Phuket to Surat Thani), so most trips stick to one coast.
When is the best time to go island hopping in Thailand?
The two coasts have opposite seasons. The Andaman (Phuket, Krabi, Phi Phi, Lipe) is driest from November to April. The Gulf islands (Samui, Phangan, Tao) are best from roughly January to September and wettest from October to December — so there is good island weather somewhere most of the year.
How do you get between the islands?
By ferry and speedboat, booked online in advance in high season or at piers and travel agents on the spot. Many routes sell combined boat-and-bus tickets through platforms like 12Go. Speedboats are faster but pricier and rougher; big ferries are slower and steadier.
