Thailand / Islands · 16 min read
The Similan Islands keep office hours. Everything else follows from that.
Two coasts with opposite seasons, nine islands, and the month you are free deciding all of it.
In this guide
Thailand’s Two Coasts Have Opposite Seasons
The rain reaches them at different times, and that is the whole trick.
The Similan Islands keep office hours. The national park's listing admits visitors between 8am and 4pm, from 15 October to 15 May, and caps the day at 3,325 people. For the other five months the islands are shut and the reef is left alone. Across the peninsula, in the Gulf, Koh Samui runs to the reverse calendar: its heavy rain starts as the Similans reopen and peaks in November.
That mismatch is the whole trick to choosing among the best islands in Thailand. The country has two coasts and two monsoons, and a beach that matches the brochure in February can be under red flags, with the speedboats tied up, in August. So this guide asks for your month first and gives you the island second: eight sections, ten places, and my pick for each stretch of the year. Our ranking of the best islands in Southeast Asia sets Thailand's against the neighbours'.
The two coasts, and what they look like
Thailand's beaches face two different seas, and the rain reaches them at opposite ends of the year. UK government travel advice puts the rainy season at May to October, generally, then makes an exception for Koh Samui and the south-east, where it usually falls between November and March. Samui's heaviest rain, most guidebooks agree, comes from October to December. The calendar is enforced as well as forecast. The Similans close from 16 May to 14 October, Maya Bay shuts for August and September, the speedboats to Koh Lanta stop from about May, and Koh Kood's boat timetable halves on 16 May.
This week shows how it works at the edges. On 9 October 2026 Khaosod English reported the Thai Meteorological Department's forecast to 15 October: the southwest monsoon still sitting over both the Andaman Sea and the Gulf, heavy rain across the south, waves above two metres in thunderstorms and small boats told to keep clear. Late October and May are the gambles, and I'd only take them with dates that can move. The British advice adds that the weather has become less predictable, so read the table below as odds. It splits the Gulf in two, because the Trat islands near Cambodia keep roughly the Andaman's dry months. For the neighbours' calendars, see our month-by-month guide to Southeast Asia.
Every month, sortable
| Months | Andaman coast | Samui, Phangan, Tao | Trat islands | My pick |
|---|---|---|---|---|
| November–December | Dry season begins; parks and boats are back | Wettest weeks; sailings get cancelled | Dry; full boat timetable | Koh Lanta or Koh Kood |
| January–February | Driest and busiest | Clearing; showers can linger | Dry; the recommended window | Koh Lipe or Koh Yao Noi |
| March–April | Hot and calm | Dry | Hot; boats still frequent | Koh Lanta, and the Similans before 15 May |
| May–June | Monsoon starts; parks shut mid-May | Dry | Rain starts; boats halve from 16 May | Koh Samui |
| July–August | Rough seas and red flags | Mostly dry; school-holiday crowds | Wet; reduced boats | Koh Phangan or Koh Tao |
| September–October | Wettest; reopening from mid-October | Rain building through October | Wet until mid-October | Phuket Town for food, or wait |
Koh Lanta: The Pick for a Long Stay
Two islands joined by a bridge, and no airport on either.
Two islands make up Lanta, in Krabi province, joined to each other by a bridge since 2016 and to the mainland by a car ferry. Visitors mean Koh Lanta Yai, the long thin one, with its beaches strung down the west coast. Muslim-Thai, Chinese-Thai and Urak Lawoi families share it; Travelfish dates the Urak Lawoi's seafaring ancestors to the 16th century.
The same guide describes a west coast that is plainly touristy and still low-key enough for families who want some comforts and not too many. Scandinavian backpackers found the place in the 1980s, Swedes remain a large share of the guests, and a yoga scene followed. Away from the sand it reports mosques, longtail boats and roadside food heavy on the chilli. The national park at the southern tip charges foreigners 200 baht (about $6) and has a lighthouse at the end of Ta Nod Beach, according to the Thai National Parks listing.
Fly to Krabi and take a minivan that rides the car ferry: 350 to 450 baht ($10 to $13) and two to four hours, year-round, on 2026 figures from Byklo, a scooter-rental firm that publishes a route guide. Its advice is to avoid midday and late afternoon in peak season, when the ferry queue can reach 60 to 90 minutes. Passenger boats from Phuket, Ao Nang and Krabi Town sail only from November to April. I'd give Lanta a week at least.
Nothing here photographs like Maya Bay, and there is no airport. Come between May and October and the speedboats have stopped and most of the park's smaller islands are closed. Most residents are Muslim, so cover up in the villages.
Koh Rok, two small islands 26km to the south and part of the same park, is the day trip. Group speedboat tours start around 1,400 baht ($42) and take about an hour; the park's listing warns against the two-hour longtail. It is closed from 1 June to 30 September.
The best islands in Thailand by coast: ten places in this guide
Koh Lipe Has the Best Beaches, and the Crowds Know
The bottom of the Andaman coast, in the Tarutao marine park.
Lipe sits at the bottom of the Andaman coast in Satun province, in the waters of Tarutao National Park and about 90 minutes by ferry from Langkawi in Malaysia. Two beaches define it, Sunrise and Pattaya, the longest on the island. Everyone who lands pays a 200 baht (about $6) park fee, good for five days.
Travelfish rates those two beaches among the best in the country, then spends its opening paragraphs on what has happened behind them. Mainstream tourism arrived in the late 2000s and, by its account, the island went from dirt paths to crowded roads lined with concrete at startling speed. Guests now come mostly from China, Malaysia and Thailand, weekends are the busy days, and the bars are a notch more grown-up than Phi Phi's. Beyond the sand the draw is the water: boat tours reach 21 nearby islands for snorkelling and diving.
From the Thai side, speedboats leave Pak Bara pier and take between 75 minutes and two hours for 500 to 700 baht ($15 to $21), on fares the same site listed in January 2026. From Malaysia, The Island Drum's Vanessa Workman says the Langkawi ferries run from about mid-October to late May, stop at an offshore platform and hand you to a longtail for roughly 50 baht; immigration is a desk on Pattaya Beach. I'd arrive midweek with the first night booked, as she suggests.
This is open sea. The site's ferry notes warn that the weather can get wild and that you will probably arrive wet, so bag the electronics and take the seasickness pill before boarding. Outside the Langkawi season, the journey from anywhere else in Thailand is long.
Taking the Langkawi boat means a fresh entry into Thailand. Since 15 September 2026 the UK government's entry page says visa-exempt tourist entries are normally limited to two per calendar year; the law firm Siam Legal reads the cap as applying to land crossings. Until that is settled, count the hop as one of yours.
Koh Yao Noi: The Quiet Island Closest to Phuket
Midway between Phuket and Krabi, and nothing like either.
Yao Noi lies in Phang Nga Bay, roughly midway between Phuket and Krabi. Willy Thuan of Phuket 101, who has lived in Phuket since 1994, measures it at about 12km by 5km with some 5,000 residents, most of them Muslim, living from fishing, rubber, rice and coconuts. Tourism is the newcomer.
Thuan is blunt about what you get. The beaches are all on the east coast, none is a wide white postcard, and at low tide the sea retreats so far that swimming is off. The compensation is a sandbank that surfaces between Tha Khao Beach and the islet of Koh Nui, and the view east to the bay's limestone towers that every guidebook photographs. The roads are paved, flat and nearly empty, the rice fields are greenest in July, and there is no bar strip. 'Koh Yao Noi is not a party island,' he writes.
Speedboats leave Bang Rong Pier on Phuket's east coast between 8.40am and 5pm, take about 30 minutes and cost around 300 baht ($9), landing at Manoh Pier. Rent a scooter for 250 to 350 baht a day; the full loop takes under two hours. For dinner his first choice is Tha Ton Do Seafood, on stilts over the mangroves. Bring cash, because the ATMs can run dry on busy weekends.
Quiet has a price. Three of the best-known places to stay are five-star: Six Senses Yao Noi, Cape Kudu and 9 Hornbills Tented Camp. Alcohol is limited, the villages expect modest dress, and September and October bring the most rain and the most cancelled boat trips.
The quiet islands, and what quiet looks like
Phuket Is the Island to Eat On, Then Leave by Boat
The one beach purists dismiss, and the one with the Michelin listings.
Thailand's largest island is the one beach purists like to dismiss. I'd stop for the kitchens. UNESCO made Phuket a Creative City of Gastronomy in 2015 and puts food's contribution to the local economy at $3.6 billion a year, on an island of about 390,000 people. It also has the airport and the piers for everything to the east and south.
The evidence is in Phuket Town, away from the beach strips. The 2026 Michelin Guide lists 18 Bib Gourmand addresses on the island, its award for good cooking at modest prices, and nine of them cook southern Thai food; the rest include two roti shops and a congee house. One Chun, in a 19th-century building on Thep Krasatti Road, works from family recipes. The inspectors single out crab meat in yellow curry with coconut milk, and mu hong, the town's pork belly stew, for its 'bold flavours and soft, tender pork belly'.
Give Phuket Town two nights at the start of an Andaman trip. One Chun opens daily from 10am to 10pm, an hour less on Tuesdays; it takes cash only and wants a phone call for a table. Then use the island as a pier. Boats for Koh Yao Noi go from Bang Rong, and the November-to-April speedboats for Phi Phi and Koh Lanta go from Rassada. For what is in the bowl, our guide to Thai curry types helps.
Rain finds the town quickly. On 9 October 2026, Khaosod English reported, under an hour of it flooded Ranong Road outside Jui Tui Shrine and broke up a Vegetarian Festival street-food event. On the west coast, British travel advice is that people have drowned in riptides, so obey the red flags.
Koh Samui: The Best Island for July and August
The only one of the three Gulf islands with an airport.
Of the three southern Gulf islands, only Samui has an airport, which Travelfish says handled more than 2.5 million passengers in 2025. It also has over 1,000 hotels and guesthouses. In July 2026 the readers of Travel + Leisure voted it the world's best island, a fraction of a point ahead of the Maldives.
The guide's own summary is cooler than that award. It traces the island from a 1970s backpacker stop to wine bars, clubs and some of the country's most luxurious resorts, and says plainly that crowds and overdevelopment came with them. Lamai is the beach it rates highest, with Thong Ta Kien and Bang Po as alternatives. The scale shows at the edges: Khaosod English counted 58 to 60 flights a day over New Year, and more than 40 taxi drivers fined for overcharging or refusing the meter.
Use Samui when the Andaman is shut, from May to September, and base yourself at Lamai. Flying in is quick and priced accordingly, because Bangkok Airways runs the airport as a private concession; fares from Bangkok start around $70 one way. The cheap route is the car ferry from Donsak on the mainland, which Raja Ferry lists at 220 baht (about $6.60) for a 90-minute crossing to Lipa Noi.
Water. Rationing began on 3 August 2026, with the mainland pipeline delivering about 16,000 cubic metres a day against demand of 34,000, Travelers Today reported from the waterworks authority's figures. Ask your hotel how it is supplied before you pay a deposit.
Samui in November. The month averages about 445mm of rain, and in November 2025 Pattaya Mail reported Lomprayah and Lotus Ferry cancelling Surat Thani–Koh Tao sailings as rough seas closed the route for days. If November is your only window, book the Andaman.
Koh Phangan and Koh Tao: The Gulf on a Smaller Budget
Two islands without airports, north of Samui.
North of Samui come two islands without airports. Phangan is the bigger, with more than a dozen bays and a following built since the mid-1980s by backpackers who thought Samui too developed. Tao is the small one and it exists for diving: at one point it issued the second-highest number of dive certifications a year in the world.
Travelfish once joked that Tao was 'a drinking island with a diving problem' and now says it has grown up, drawing families, freedivers and snorkellers; only Malaysia's Perhentians, it reckons, have cheaper diving in Southeast Asia. Its Phangan page sells a green interior, affordable rooms and a relaxed mood, with bays that run from built-up and party-minded to hideaways. The party is at Haad Rin, home of the Full Moon nights and, per Khaosod English, a New Year's Eve countdown.
Raja Ferry lists the car ferry from Donsak to Thong Sala on Phangan at 290 baht (about $8.70) and two and a half hours. Lomprayah's high-speed ferries link Samui's Pralarn Pier with Phangan, and Donsak and Chumphon with Tao. Book ahead for late December, when the paper found nearly every Lomprayah departure sold out. On Phangan, choose the bay before the bungalow. For how its nights compare, see our guide to nightlife across Southeast Asia.
UK government advice says assaults are most common during full moon parties and near bars late at night, and that drinks get spiked. Go with friends, watch your glass and arrange the ride home first. Vapes are illegal in Thailand, with fines of up to 30,000 baht (about $900).
Koh Kood Is the Quiet Island I Would Choose, Border Permitting
Close to the Cambodian border, which is the complication.
At the bottom of the Koh Chang group in Trat province, Kood lies close to the Cambodian sea border. No car ferry serves it. The guide site Explore Koh Chang lists passenger boats only, from Laem Sok pier, and sets it against its neighbours: Koh Chang larger and busier, Koh Mak flat and made for bicycles.
Travelfish, which last worked the island on the ground in late 2023, found refurbished fishermen's huts in the mangroves, family-run beach bungalows that have barely changed in decades and a few expensive resorts. On a calm day, it says, the turquoise water and coral sand could pass for the Maldives, and the inland waterfalls are best in the wet months. The most famous resort, Soneva Kiri, now Kiri Private Reserve, is shut for renovation until late 2026, according to Explore Koh Chang.
Boonsiri, Koh Kood Express and Seudamgo cross from Laem Sok in about an hour for 500 to 600 baht ($15 to $18); a bus-and-boat ticket from Bangkok's Khao San area is about 1,100 baht ($33). Go between November and February. From 16 May to 15 October the sailings halve and the speedboats stop, on the 2025–26 timetable.
The border. Every land crossing to Cambodia has been shut since June 2025 and a ceasefire has held, shakily, since 27 December, The Thaiger reported; it found no violence on the islands. The Foreign Office now advises against all but essential travel within 20km of the land border and names no island. Ask your insurer.
The east, and the Gulf, at their emptiest
The Similans and Maya Bay: Islands With a Closing Date
Two of the best-known beaches in the country sit on park land that shuts.
Two of the best-known beaches in the country sit on national park land that you may only visit by day. The Similans, off Khao Lak, open from 15 October to 15 May, and nobody has slept on them since 2018. Maya Bay, on uninhabited Phi Phi Leh, shuts every year from 1 August to 30 September.
Phuket 101's Willy Thuan describes the Similans as warm, very clear water over coral, with sea turtles a regular sight and a boulder viewpoint on Ko Similan worth the short climb. Maya Bay, which he first saw in the early 1990s, he calls a very different experience now: boats may no longer anchor off the sand, tours allow about an hour ashore and you may wade only to the knee. He still thinks the bay looks beautiful again since it reopened.
For the Similans, sleep in Khao Lak. Speedboats leave Thap Lamu pier and take 60 to 90 minutes; from Phuket you add a 90-minute drive. The park fee is 500 baht (about $15) for foreign adults and 250 for children, usually folded into the tour price. Thuan's timing is late October or November, before the busy months, and his seat is at the back of the boat, pill already taken. I'd choose one of the two.
These places close because visitors wore them out: Ko Tachai, in the same park, has been shut since 2016 after reef damage. Early in the season the sea can also say no. Khaosod's forecast for this week had waves above two metres in storms.
What to Eat and Drink on the Islands
Island menus follow the people who live there.
Island menus follow the people who live there. Several Andaman islands are majority Muslim: Lanta's roadside stalls go heavy on the chilli, and on Koh Yao Noi the cheapest dinner is the Tha Khao night market, open from about 6pm to 8pm, while Pradu Seafood sells no alcohol and lets you bring your own. Phuket Town is the serious stop, with those nine southern Thai Bib Gourmands plus roti and congee for breakfast. On Samui, where the wine bars are, I'd order from the Thai page of the menu; our piece on Thai street food beyond pad thai is a crib sheet.
Drink has rules. Alcohol sales are restricted between midnight and 11am outside licensed hotels and entertainment venues, and the British advice on bootleg spirits is short: 'Even small amounts of methanol can kill.' I'd keep to sealed beer and leave the beach buckets to braver livers.
Three Island Routes That Fit a 30-Day Stamp
One for each season, and none of them rushed.
November to April, the Andaman chain: two nights in Phuket Town, three on Koh Yao Noi, a week on Koh Lanta, then Koh Lipe. Speedboats from Lanta to Lipe start at 1,150 baht ($34) and take from two and a half hours, on January 2026 listings.
May to September, the Gulf: fly or ferry to Samui for three nights at Lamai, cross to Phangan for as long as the bay holds you, and finish on Tao, leaving north by fast ferry to Chumphon.
November to February, the east: Bangkok to Koh Kood by bus and boat in a day, then back up through Koh Mak and Koh Chang. Since late May 2026 the Koh Chang car ferries have sailed only when full, apart from fixed 6.30am and 6.30pm departures, a fuel-saving measure reported by Explore Koh Chang.
All Nine, Side by Side
Coast, month, who it is for, and roughly what it costs.
Every island, sortable
| Island | Coast | Go in | Best for | Price |
|---|---|---|---|---|
| Koh Lanta | Andaman, Krabi | November–April | A long, easy stay; families | ฿฿ |
| Koh Lipe | Andaman, far south | November–April | The best sand; a Langkawi combination | ฿฿ |
| Koh Yao Noi | Andaman, Phang Nga Bay | November–April | Quiet, 30 minutes from Phuket | ฿฿฿ |
| Phuket | Andaman | November–April | Southern Thai food; flights and piers | ฿฿฿ |
| Koh Samui | Gulf | January–September | Families; July and August | ฿฿–฿฿฿ |
| Koh Phangan | Gulf | January–September | Cheap long stays; yoga; the party | ฿ |
| Koh Tao | Gulf | January–September | Dive courses | ฿ |
| Koh Kood | Eastern Gulf, Trat | November–February | Doing very little | ฿฿ |
| Similan Islands | Andaman Sea, off Khao Lak | 15 October–15 May | A snorkelling day trip | 500 baht park fee |
| Maya Bay | Andaman, Phi Phi Leh | October–July | An hour on a famous beach | Fee in tour price |
Price bands describe rooms, using how the sources in each section characterise the island: ฿ where budget bungalows and cheap diving set the tone; ฿฿ where there is a full spread from bungalows to resorts; ฿฿฿ where five-star resorts dominate or costs run above the Thai norm. No nightly rates were verified for 2027.
Seasons, Entry Rules, Boats and Money
The practical layer underneath all of it.
When to go: November to April for the Andaman coast, January to September for Samui, Phangan and Tao, November to February for Koh Kood. The season is turning as this is published: on 9 October 2026 the Thai Meteorological Department still had the southwest monsoon over both seas, with heavy rain forecast in the south until the 15th.
Entry rules: Since 15 September 2026, visa-free entry for British travellers is 30 days, for tourism only, the UK government's entry page confirms; the law firm Siam Legal lists 60 nationalities on the same terms, down from 60 days, and a single 30-day extension at 1,900 baht ($57). File the Thailand Digital Arrival Card online in the three days before you land. You may be asked to show 10,000 baht (about $300) and an onward ticket.
Getting around: Ferries are the weak point. The same advice says boats have sunk and collided, blaming overloading, poor maintenance and rough monsoon seas, so skip a crossing that looks overfull. To ride a scooter legally, British visitors need a 1968 international driving permit with their home licence, and a helmet.
Money: The baht stood at about 33.5 to the US dollar on 11 October 2026. Carry cash on the small islands and keep your park-fee receipts.
Safety: Neither Britain nor the United States advises against visiting the islands in this guide. London's warnings cover Pattani, Yala and Narathiwat, part of Songkhla and the 20km strip along the Cambodian land border; Washington rates Thailand Level 1, with Level 2 for those two areas. Bangkok is the live problem. All 50 districts were declared disaster areas after late-September floods, so check before planning a stopover around our Bangkok food guide.
The Bottom Line
Pick the month, then the coast, then the island.
The best island in Thailand depends on the week you are free. From November to April I'd fly to Phuket, eat for two days and take boats south to Koh Lanta. From May to September I'd turn the map around and base myself in the Gulf, on Samui for ease or Phangan for value. Koh Kood is the one I'd save for a winter when the border is calm. Whatever the brochure shows, the monsoon has the casting vote, and the national parks have already written it into their opening hours.
Pick the month, then the coast, then the island.
Before you go
What is the best island in Thailand for first-timers?
Koh Lanta between November and April, and Koh Samui between May and September. Lanta has long beaches, a year-round road-and-ferry link from Krabi airport and enough comfort for families without the bulk of Phuket. Samui has the airport and the hotels when the Andaman coast is in its monsoon. Choose by month before you choose by photograph.
Which Thai islands are best in July and August?
The Gulf islands: Koh Samui, Koh Phangan and Koh Tao. Their heavy rain falls from October to December, the reverse of the Andaman coast, where the southwest monsoon runs from about May to October, the Similan Islands are closed and Maya Bay shuts on 1 August. Book boats and beds early, because everyone else has read the same calendar.
Is it safe to visit Koh Kood and Koh Chang in 2026?
Ferries and hotels are operating and no fighting has been reported on the islands, but check the advisory map before you book. The UK advises against all but essential travel within 20km of the land border with Cambodia and does not name the Trat islands; its earlier 50km zone was read as covering them. Confirm with your insurer that your route, mainland pier included, is covered.
How many days do you need for island-hopping in Thailand?
Two weeks covers three islands on one coast without rushing. Since 15 September 2026 the visa-free stay has been 30 days, so a month is the ceiling unless you pay 1,900 baht for an extension. I'd allow at least four nights an island, because every crossing eats half a day and boats are the first thing the weather cancels.
Is Phuket worth visiting, or should you skip it?
Worth two nights, in Phuket Town, for the food. The island has 18 Bib Gourmand restaurants in the 2026 Michelin Guide, nine of them southern Thai, and UNESCO has listed it as a Creative City of Gastronomy since 2015. I'd eat there on arrival, then take a boat to Koh Yao Noi or Koh Lanta for the beach part of the trip.
When do the Similan Islands open?
From 15 October to 15 May each year, between 8am and 4pm, with no overnight stays. The park can close early in bad weather and caps visitors at 3,325 a day. Foreign adults pay 500 baht. Day trips leave from Thap Lamu pier near Khao Lak, a speedboat ride of 60 to 90 minutes each way.
Keep going
Sources
Checked against official and institutional sources · Tourism Authority of Thailand · Thai Department of National Parks · UK FCDO Thailand travel advice · US State Dept Thailand · Thai Immigration Bureau · Thai Meteorological Department · MICHELIN Guide Phuket · Bank of Thailand exchange rates · UNESCO: Thailand · WHO: Thailand country profile
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