TL;DR: Thailand’s islands split into two coasts that almost never share good weather at the same time. The Andaman coast (Phuket, Phi Phi, Krabi/Railay, Koh Lanta, Koh Lipe, the Similans) is best November-April and rough or partly closed May-October; the Gulf coast (Koh Samui, Koh Phangan, Koh Tao, Koh Chang) is best roughly June-September, with its own rainy patch October-December when the northeast monsoon hits. Phuket is the easiest to reach, with its own international airport; Koh Samui has the only other island airport; everywhere else means a ferry, most running ฿200-1,200 (US$6-36) and 30 minutes to 2.5 hours. Koh Tao is the cheapest place in the world to get PADI-certified (about ฿10,000-12,000 / US$300-360 for Open Water); Koh Phangan is the party pick (Full Moon Party); Koh Lipe and Koh Lanta are the quieter, more laid-back choices; Koh Chang suits a family trip within reach of Bangkok. All prices at ฿33 = US$1 (July 2026).
Thailand has hundreds of islands scattered along its Andaman and Gulf coasts, but almost every “best islands in Thailand” search comes down to nine names: Phuket, Phi Phi, Koh Samui, Koh Phangan, Koh Tao, Koh Lipe, Koh Lanta, Koh Chang, and the Similans/Railay area near Krabi. Most guides rank them as if they’re interchangeable. They aren’t: they sit on two different coasts of the Thai peninsula, the Andaman Sea to the west and the Gulf of Thailand to the east, and the two coasts run on opposite weather clocks. Pick the wrong coast for your travel month and you can land in the middle of a monsoon on an island that was “the best” in every blog post.
This guide compares all nine by what each is genuinely best for (diving, parties, families, or quiet), which coast they’re on, the season that works for each, and exactly how to get there, with real ferry prices and times.
Table of Contents
- Island comparison table
- Andaman vs Gulf: why the coast matters more than the island
- Which island is best for diving?
- Which island is best for nightlife and parties?
- Which island is best for a quiet, relaxed trip?
- Which island is best for families?
- How do you get to each island?
- Honest downsides of island-hopping in Thailand
- FAQ
Island comparison table
| Island | Coast | Best for | Best season | How to get there |
|---|---|---|---|---|
| Phuket | Andaman | Gateway/base, beaches, day trips | Nov-Apr | Own international airport (HKT) |
| Phi Phi | Andaman | Scenery, snorkeling, day trips | Nov-Apr | Ferry from Phuket (~1-1.5 hrs, from ~฿450/US$14) or Krabi |
| Railay (Krabi) | Andaman | Rock climbing, beach scenery | Nov-Apr | Longtail boat from Ao Nang (~15 min, ฿100/US$3 one-way) |
| Koh Lanta | Andaman | Quiet, long beaches, families | Nov-Apr | Ferry from Krabi (~1-3 hrs, from ~฿450/US$14) |
| Koh Lipe | Andaman | Quiet, clear water, snorkeling | Nov-Apr (many businesses shut May-Oct) | Ferry from Pak Bara pier near Satun (~1.5 hrs, from ~฿1,200/US$36) |
| Similan Islands | Andaman | Diving, snorkeling day trips | Mid-Oct to mid-May only (closed rest of year) | Speedboat day tour from Phuket/Khao Lak (~1.5-3 hrs, ฿2,500-4,000/US$76-121) |
| Koh Samui | Gulf | Base, resorts, easy access | Jun-Sep (year-round-ish) | Own airport (USM), Bangkok Airways from Phuket/Bangkok |
| Koh Phangan | Gulf | Parties (Full Moon Party), beaches | Jun-Sep | Ferry from Koh Samui (~30-45 min, from ~฿200-300/US$6-9) |
| Koh Tao | Gulf | Diving/snorkeling, budget certification | Jun-Sep | Ferry from Koh Phangan (~1-1.5 hrs, from ~฿390/US$12) or Koh Samui |
| Koh Chang | Gulf (eastern) | Families, budget trip near Bangkok | Nov-Apr (its own dry season) | Ferry from Trat’s Ao Thammachat pier (~30-45 min, ฿80/US$2.40) |
Ferry prices are one-way, foot-passenger, low season to shoulder season; expect higher fares and sell-outs around Full Moon Party dates and Thai holidays. See Sources for each figure.
Andaman vs Gulf: why the coast matters more than the island {#andaman-vs-gulf}
Thailand’s coastline runs two separate monsoon systems, and they’re roughly opposite each other.
The Andaman coast (Phuket, Phi Phi, Krabi/Railay, Koh Lanta, Koh Lipe, the Similans) faces the Indian Ocean. Its rainy season runs April to October (southwest monsoon, September-October wettest); November-April is calm, dry, peak season. The Similan Islands National Park physically closes to all visitors mid-May to mid-October every year, so a Similans trip only works November-April.
The Gulf coast (Koh Samui, Koh Phangan, Koh Tao) sits on the peninsula’s other side and largely dodges that monsoon, making June-September its best stretch, exactly when the Andaman is wettest. But the Gulf has its own rainy season, the northeast monsoon, October-December, when Samui, Phangan, and Tao see rough seas and ferry disruptions. Koh Chang, also Gulf but far enough east to run on Trat’s weather system, lines up closer to the Andaman’s calendar: November-February is best, July its wettest month.
Never plan a Thailand island trip by island name alone; check the coast and the calendar together. For the month-by-month breakdown across the whole country, see outthailand.com’s best time to visit Thailand guide.
Which island is best for diving? {#best-for-diving}
Koh Tao (Gulf) is Thailand’s dive capital; the Similan Islands (Andaman, open November-April only) are the other major draw.
Koh Tao has the country’s highest concentration of dive schools relative to its size, and PADI Open Water certification runs roughly ฿10,000-12,000 (US$300-360), covering e-learning, training dives, equipment, and the certificate, among the least expensive places in the world to get certified. Its reefs are shallow and forgiving for beginners, with sites like Chumphon Pinnacle and Sail Rock also drawing certified divers back for whale shark sightings.
The Similan Islands, reached by speedboat day tour from Phuket or Khao Lak (roughly 1.5-3 hours each way, ฿2,500-4,000 / US$76-121 per person including gear and lunch), offer some of the clearest water and best-preserved reefs in the Andaman Sea, but the national park is fully closed mid-May to mid-October every year, so this only works November-April. Koh Lanta’s surrounding reefs are a solid, less crowded alternative when the Similans are shut.
Which island is best for nightlife and parties? {#best-for-parties}
Koh Phangan, home of the Full Moon Party, and Phuket’s Patong strip are the two major party bases.
Koh Phangan’s Full Moon Party on Haad Rin beach is one of the most famous recurring parties in the world, drawing thousands of visitors on the night of (or closest to) each full moon, with beach bars, fire shows, and buckets of mixed drinks running until sunrise. Ferries and rooms both spike in price and sell out around each Full Moon date, so book ahead. Phangan also runs smaller Half Moon and Jungle Experience parties on other nights.
On the Andaman side, Phuket’s Patong Beach is the country’s other major nightlife hub, dense with bars, clubs, and the Bangla Road strip, and it works year-round since its mostly-indoor nightlife isn’t weather-dependent the way an outdoor beach party is.
Which island is best for a quiet, relaxed trip? {#best-for-quiet}
Koh Lipe and Koh Lanta (both Andaman) are the calmest, least developed picks among the major islands.
Koh Lipe, far south near the Malaysian border, has some of the clearest turquoise water in the country and a walkable main village, genuinely laid-back compared to Phuket or Phi Phi. The trade-off is access and seasonality: reached only by ferry from Pak Bara pier near Satun (roughly 1.5 hours, from about ฿1,200 / US$36 one-way), and many businesses close during the May-to-October low season, when rough seas also shut down many surrounding islands’ snorkeling trips.
Koh Lanta offers a similar slower pace with easier access, a 1-3 hour ferry from Krabi (from about ฿450 / US$14), long uncrowded beaches, and a more developed but still low-key resort scene.
Beyond these nine, two smaller islands go even quieter. In the Gulf near the Cambodian border, Koh Kood has clear water and next to no nightlife, while over on the Andaman side in Phang Nga Bay, Koh Yao Noi sits within day-trip reach of Phuket and Krabi but keeps a slow, fishing-village pace neither of the bigger islands can match.
Which island is best for families? {#best-for-families}
Koh Chang and Koh Lanta are the two standout family picks.
Koh Chang, Thailand’s second-largest island, sits in the eastern Gulf near Trat and is reachable from Bangkok by road and a short ferry from Ao Thammachat pier (about 30-45 minutes, ฿80 / US$2.40 one-way, cash only) without needing a flight, useful for a shorter trip with young kids. Its long, gently sloping beaches, lower prices than Phuket or Samui, and calmer pace round it out as a solid family base, best visited November to February.
Koh Lanta’s similarly long, flat beaches and low-key resort strip make it the Andaman-side equivalent, best November-April.
How do you get to each island? {#how-to-get-there}
Phuket and Koh Samui are the only two islands with their own airports; every other island on this list is ferry-only from a mainland pier or a neighboring island.
Phuket International Airport (HKT) is Thailand’s main island gateway, with direct international flights from across Asia, Australia, the Middle East, and Europe, plus frequent domestic connections from Bangkok. It doubles as the base for day trips to Phi Phi, Railay/Krabi, and the Similans.
Koh Samui Airport (USM) is the only other island airport, served mainly by Bangkok Airways, with around 50-60 direct flights a week from Phuket (about 55 minutes) plus frequent Bangkok flights. From Samui, Koh Phangan is a 30-45 minute ferry (from ~฿200-300 / US$6-9), and Koh Tao a further 1-1.5 hour ferry (from ~฿390 / US$12).
Everywhere else runs on ferries and longtail boats:
- Phuket to Phi Phi: ~1-1.5 hours, from ฿450 (US$14) one-way.
- Ao Nang (Krabi) to Railay Beach: ~15 minutes by longtail, ฿100 (US$3) daytime, surcharge after 6:30pm.
- Krabi to Koh Lanta: ~1-3 hours depending on service, from ฿450 (US$14).
- Pak Bara pier (near Satun) to Koh Lipe: ~1.5 hours, from ฿1,200 (US$36); the only realistic way in without a private charter.
- Trat’s Ao Thammachat pier to Koh Chang: ~30-45 minutes, a flat ฿80 (US$2.40), cash only.
There’s no direct ferry between an Andaman island and a Gulf island, since they sit on opposite sides of the peninsula; combining both means routing through a mainland hub, typically a short domestic flight between Phuket and Koh Samui. See outthailand.com’s Thailand itinerary guide for routing a mainland trip around an island add-on.
Honest downsides of island-hopping in Thailand {#honest-downsides}
- The two coasts rarely have good weather at the same time. A trip spanning both an Andaman and a Gulf island will likely hit a rainier window on one leg.
- Ferries get cancelled or rough in shoulder season. Late Andaman crossings (September-October) and the Gulf’s October-December window can both see delays; build in slack around any connecting flight.
- The Similans are a hard closure, not a soft one. Mid-May to mid-October, the park is shut to all visitors, no exceptions.
- Popular islands get crowded and pricier in peak season. Phi Phi, Phuket’s main beaches, and Phangan around Full Moon Party dates all see price spikes and sold-out ferries.
- Cash still rules many piers. Longtail boats to Railay and the Koh Chang ferry are cash-only at departure.
- “Quiet” islands partly shut down in low season. A real share of Koh Lipe’s businesses close May-October, so check what’s actually open before chasing an off-season bargain.
FAQ
What is the best island in Thailand overall?
It depends on the goal: Koh Tao for diving, Koh Phangan for Full Moon Party nightlife, Koh Lipe or Koh Lanta for quiet, Koh Chang for families. Phuket wins on convenience, with the only major international airport and easy day trips to Phi Phi, Railay, and the Similans.
Should I go to Phuket or Koh Samui?
Match it to season. Phuket (Andaman) is best November-April; Koh Samui (Gulf) is best roughly June-September. Both have their own airports. If your dates land in the Andaman’s rainy season, Samui is the safer bet, and vice versa for the Gulf’s October-December rains.
Is Koh Phi Phi worth visiting?
Yes, for the scenery, but expect crowds. Its limestone cliffs and Maya Bay, the cove made famous by The Beach, are among Thailand’s most photographed, a 1-1.5 hour ferry from Phuket (from ~฿450 / US$14) or Krabi. Prices run higher than neighboring islands, so most visitors treat it as a day trip or one overnight.
What is the cheapest Thai island to visit?
Koh Chang and Koh Lanta run cheaper than Phuket, Phi Phi, or Koh Samui on rooms and food. Koh Tao is unusually good value for divers: PADI Open Water certification runs about ฿10,000-12,000 (US$300-360), among the lowest prices for that certificate anywhere.
Which Thai islands are best for diving?
Koh Tao (Gulf) is Thailand’s dive capital, with Open Water certification from ~฿10,000-12,000 (US$300-360). On the Andaman side, the Similan Islands (open November-April only) and Koh Lanta’s nearby reefs are the other major draws.
Which Thai islands are best for a family trip?
Koh Chang and Koh Lanta: both have long, gently shelving beaches and a lower-key pace than Phuket or Phangan. Koh Chang is also reachable from Bangkok by road and a short ferry, without flying.
Can I visit an Andaman island and a Gulf island in one trip?
Yes, but budget for a domestic flight rather than a direct ferry, since the coasts sit on opposite sides of the peninsula. A common route: Bangkok to Phuket (plus Phi Phi or Railay), then a short flight to Koh Samui (plus Phangan or Tao). Check the season on both legs first.
Do I need to book Thailand island ferries in advance?
For short, frequent routes like Ao Nang to Railay or Krabi to Koh Lanta, buying on the day at the pier is fine. For Full Moon Party nights, Similan day trips, or Pak Bara to Koh Lipe in shoulder season, book a few days ahead.
Before you book
Choosing a Thailand island trip comes down to matching three things: what you actually want to do (dive, party, relax, or bring the kids), which coast that island sits on, and whether your dates fall in that coast’s good season. Align those three and almost any island on this list delivers; get them out of sync and even “the best island in Thailand” can mean a washed-out week.
For the wider trip this fits into, see outthailand.com’s best time to visit Thailand guide for the full national picture, the best places to visit in Thailand guide for how the islands stack up against Bangkok and Chiang Mai, and the Thailand itinerary guide for routing an island add-on around a mainland trip. Once your dates are set, check outthailand.com’s live events listings for what’s happening on the ground while you’re there.
Sources
- Ferryhopper: Phuket - Phi Phi Islands ferry: duration and pricing, Phuket to Phi Phi
- Direct Ferries: Phuket to Koh Phi Phi: ~1-1.5 hr crossing, ฿450 fare reference
- Direct Ferries: Koh Samui to Koh Phangan: 30-37 min crossing time
- Phanganferries.com: Koh Samui to Koh Phangan: fares from ~฿200
- Lomprayah: Timetable 2026: Koh Phangan-Koh Tao schedule
- Phanganferries.com: Koh Phangan to Koh Tao: fares from ฿390, ~1-1.5 hr
- Ferry Lipe: Ferry Timetable: Pak Bara to Koh Lipe schedule and operators
- Direct Ferries: Pak Bara to Koh Lipe: ~1.5 hr crossing, fare range
- Aonangtravel.co.th: Krabi Town to Koh Lanta ferry ticket: ฿450 fare, 09:00-12:00 schedule
- KoLanta.net: Ko Lanta Ferry Schedule 2026: route and timing reference
- Kohchangferries.com: Koh Chang Ferry timetable: Ao Thammachat to Koh Chang schedule
- WeLoveKohChang: Ferry to Koh Chang 2026: ฿80 adult fare, 30 THB child, cash only
- 5 Star Marine Phuket: Similan Islands will close May 15th 2026: closure dates, mid-May to mid-October
- LovePhuketTours: Similan Islands Season Guide 2025-2026: reopening timing, tour pricing
- PhuketToursDirect: Similan Islands Speedboat Tour: ฿2,500 speedboat tour reference
- Backpackers Wanderlust: Ao Nang to Railay Beach 2026: ฿100 one-way, ฿200 return, evening surcharge
- CK Travels: Krabi (Ao Nang) to Railay Beach longtail boat: fare and schedule detail
- Experience Travel Group: Best Time to Visit Thailand: Andaman vs Gulf monsoon timing
- Odynovo Tours: Best Time Guide for Thailand’s Beaches & Islands: coast-by-coast season comparison
- iamKohChang: Best Thai Islands to Visit by Month: monthly climate comparison across islands
- Climatestotravel: Ko Chang climate: Koh Chang rainy season May-October, dry Nov-Feb, July wettest month
- Kohlipeisland.org: Koh Lipe Weather guide: dry/wet season split, business closures in low season
- Siam Scuba Blog: How Much Does Diving Cost in Koh Tao? 2026: PADI Open Water pricing ฿10,000-12,000
- Black Turtle Dive: PADI Diving Course Prices Koh Tao: course pricing detail
- FlightsFrom.com: Phuket to Koh Samui direct flights: Bangkok Airways frequency and duration
- Xe.com: USD/THB Currency Converter: exchange rate reference, July 2026