Which islands to visit in Thailand

Islands of limestone karst clad in deep-green forest jut dramatically out from the sea; snorkellers paddle through the shallows of secluded bays off white-sand beaches; the chatter of hornbills and langurs echoes along rainforest trails, and speedboats zip day-trippers from island to island where beach bars, dive outfits and lines of kayaks await.

Thailand has more than 1,400 islands in the south of the country, ranging from the large (Phuket, Koh Samui) to the small (Koh Kham, Koh Lipe), to tiny islets that are little more than specks in the sea. But most travellers stick to just 12 or so of the more well-known islands – many idyllic spots see relatively few visitors.

Where, then, should you make for? Our guide to which islands to visit in Thailand draws on the experience and knowledge of our specialist partners who share their tips and personal favourites based on years of travelling in the region.

Essentially, Thailand’s islands can be divided into those either side of the Kra Isthmus, the narrowest part of the Malay Peninsula. To the west are the islands off Thailand's Andaman Coast, among them Phuket, Koh Lanta and Koh Phi Phi Don. You’ll also find Krabi province on the mainland, from where many island-hoppers get underway. Then to the east of the isthmus are the islands of the Gulf of Thailand, including Koh Samui, Koh Phangan, Koh Chang and Koh Tao (unsurprisingly, koh, or ko, means island). The island groups can be subdivided into sections such as the eastern and western Gulf Islands, and further still into small archipelagos such as the Phi Phi, Chumphon and Similan archipelagos.

Laid over the islands are more than 20 marine national parks. They include Mu Ko Similan National Park which encompasses the Similan Islands in the Andaman Sea; Ao Phang Nga National Park where stands the iconic ‘James Bond Island’ Khao Phing Kan, and Mu Koh Lanta National Park, which is home to the Chao Ley people who hold animist beliefs and make their living mostly from fishing.

“Koh Tao is my favourite island, and where I learnt to dive,” says Martin. “It’s tiny and far from the mainland, with great sunsets and often a romantic vibe, not too developed.” Divers here can explore underwater caves, shipwrecks and artificial reefs. The marine life includes whale sharks, leopard sharks, green turtles and manta rays.

Mu Ko Lanta National Park boasts several excellent dive sites including Hin Daeng and Hin Muang, which are reckoned to be among the best in Southeast Asia. A mix of hard and soft corals support vibrant biodiversity, and you can witness plenty of action here, from hunting to symbiotic relationships. It’s not unknown to encounter shy octopuses tucked away into crevices. The clear waters off Koh Lipe, Koh Samui and Koh Chang are also very popular with divers and snorkellers.

“You’ve got to make for the less-frequented islands,” says Mark Ord, who with sister Lesley co-runs our partner All Points East, specialists in small group tours around Southeast Asia. “I think Koh Libong in the Trang province offers a happy medium. You’ve got good resorts there but it’s a Muslim island so you don’t have the bar scene. The villages are still centred on fishing, not tourism.”

Martin suggests tiny Koh Kye, an uninhabited island in the Bay of Chumphon. On some of our Thailand island holidays a local fisherman takes small groups to the island where you set up camp in tents on the beach, and share a bonfire and barbecue. Groups will often take part in beach cleans before they leave as well.

Koh Yao Noi and Koh Yao Yai, despite being close to both Phuket and Krabi, are quite laidback. There are some guest houses and luxury resorts, but it’s a very different vibe to the ‘party islands’. Koh Jum, an hour by ferry from Krabi, is also undeveloped and a great island to get away from it all. Like the other islands that lie off the main tourist route there’s not as much to do, but if you just want languid days on the beach, a scattering of restaurants and peace and quiet, you should be satisfied.

Thailand’s islands aren’t renowned for wildlife watching, and much of what does go on, goes on underwater. Snorkelling and scuba diving immerses you in huge, colourful shoals of fish as well as giving you chances to see larger creatures from sharks to turtles. Koh Chang and Koh Lanta, thickly forested, are good for bird watching. Nature trails on Koh Similan, largest of the Similan Islands in the Andaman Sea, can reveal langurs, squirrels and lizards, along with over 100 bird species. And 20 minutes off the coast of Trang Province by ferry lies the off-the-beaten-track island of Koh Libong. Pack a snorkel, because this is one of the last refuges for the dugong, or sea cow, a charming mammal that confines itself to coastal areas rich in the seagrass it feeds upon.

“The monsoon seasons are fairly crucial for which island group you go to,” says Mark. Thailand has two monsoon seasons which affect different parts of the country. “The best season for the Gulf of Thailand islands is from May to October,” says Mark, “and in the Andaman Sea it’s from November to April, but the east tends not to be so weather-dependent.” The monsoons also bring with them rough seas, making boat travel unpleasant, and throw around sediment underwater which means low visibility for snorkellers and divers.

Public ferry is the best way to travel between islands in Thailand. There is a well-established ferry network – Koh Trang to Koh Lipe takes about two hours, while Koh Samui to Koh Phangan takes as little as 30 minutes. In peak season (varies, but think December to April) it’s vital to book ahead through a site such as Direct Ferries because boats on popular routes are often full. They’re often small boats, too, so if you get seasick be sure to bring tablets. And if you’re connecting with a flight, make sure you allow yourself plenty of time, perhaps even 24 hours, as delays are not uncommon.

Phuket has an international airport, as does Koh Samui, though the latter is only served by a handful of airlines. Koh Trang also has an airport offering direct connections with Bangkok. There is an airport in Krabi on the west coast of southern Thailand, from where you can easily access the islands off the Andaman Coast such as Koh Lanta by ferry. And some luxury resorts have their own private airstrips, too – there is one on Koh Kood, for instance.