Visiting the Gulf of Thailand: when to go, access and itineraries

The largest and most built-up of the three, and the only one with an international airport, served mainly by Bangkok Airways. It has hospitals, malls and a wide range of accommodation. Chaweng concentrates nightlife and long beaches, while Bophut and Maenam to the north run 30 to 50 percent cheaper. Allow two to three nights for a scooter loop of the island, the Big Buddha, the Na Muang waterfall and a boat trip. It is the logical base for a first visit, covered in our recommended 5-day itinerary.

A 30-minute ferry from Samui, Phangan runs on two rhythms. In the south, Haad Rin hosts the Full Moon Party every full moon, drawing up to 20,000 people. The rest of the island is far quieter: unspoilt bays at Thong Nai Pan in the east, a yoga and wellness scene at Sri Thanu in the west, the Than Sadet waterfalls in the centre. A scooter is near essential, as the inland roads are steep and sometimes unpaved.

The smallest island, about 21 square kilometres, issues more dive certifications than almost anywhere else on earth. An Open Water course takes two and a half days and costs around 300 euros, accommodation often included. The signature sites are Chumphon Pinnacle, Sail Rock and the Koh Nang Yuan islet, reached by boat tour. Without diving, people come for the snorkelling and viewpoints; two nights are then enough.

An archipelago of 42 uninhabited limestone islets, an hour and a half by boat from Samui or Phangan. The day trip, about 40 to 50 euros, combines kayaking, snorkelling, the climb to the Koh Wua Talap viewpoint and a stop at the enclosed lagoon of Koh Mae Ko. The park partly closes from November to December at the height of the northeast monsoon. Book the day before through a beach agency.

The rail network of Thailand does not reach the islands. From Bangkok you have two options: a direct flight to Samui (1h20, 80 to 150 euros), or the night train to Surat Thani followed by a combined bus-and-ferry ticket sold all the way to your accommodation door. Chumphon, further north, is the fastest access for Koh Tao. Between islands, the Lomprayah and Seatran catamarans link Tao, Phangan and Samui several times a day.

The gulf is shielded from the southwest monsoon by the mainland: from May to September, when Phuket and Krabi are underwater, the islands stay mostly dry. The northeast monsoon, however, brings heavy rain from October to December, November being the wettest month, with flash-flood risk and cancelled crossings. December still sees showers but Christmas and New Year push rates to their yearly peak. February to April offers the calmest sea and the best underwater visibility, the window most divers aim for.