Thailand’s coastline is one of the most varied on earth. On the west, the Andaman Sea — a jewel-blue expanse studded with limestone islands, hidden lagoons, and coral reefs that rival anything in the Indo-Pacific. On the east, the Gulf of Thailand — warmer, calmer, and lined with the kind of long sandy beaches that made Koh Samui and Koh Phangan famous decades ago. Choosing between them isn’t easy, especially since each coast has its own distinct character, its own season, and its own kind of traveler.

Thailand also gets the value equation right in a way almost no other destination manages: a night in a bungalow steps from the sea costs less than a taxi ride in most Western cities, the street food is exceptional, and the diving is world-class at a fraction of what you’d pay in the Maldives or Australia. Here’s where to go.

Railay Beach — The Most Dramatic Setting in Thailand

Railay is not technically an island — it’s a peninsula near Krabi, connected to the mainland — but the sheer limestone karsts that rise from the jungle make it completely inaccessible by road. The only way in is by longtail boat from Ao Nang or Krabi Town, a 15-minute journey that already feels like arriving somewhere extraordinary. And then you round the headland and see Railay West: a perfect crescent of white sand, water the color of a swimming pool, and cliffs rising hundreds of meters on three sides.

There are four distinct beaches within Railay’s headland, each with a different character. Railay West is the main beach — the one on the postcards — with most of the accommodation and restaurants. Railay East faces the mangroves and is mainly used as the boat landing. Phranang Cave Beach, a 15-minute walk over the headland, is possibly the most beautiful stretch of sand in all of Thailand — a slim ribbon of white with a sacred cave and enormous karst formations rising from emerald water.

Railay is also Thailand’s rock climbing heartland. The limestone karsts are riddled with routes of all grades, and half a dozen climbing schools operate on the beach offering everything from beginner half-day sessions to multi-pitch adventures up faces with water views. Best time to visit: November through April on the Andaman coast. Avoid June–October when the southwest monsoon brings heavy rain and the longtails stop running.

Koh Lipe — Thailand’s Southernmost Paradise

Koh Lipe sits in the Tarutao National Marine Park near the Malaysian border — far enough south that most tourists never make it, which is exactly why it remains so good. The water around Koh Lipe has some of the best reef visibility in Thailand; the coral is in genuinely excellent health and you’ll see turtles, reef sharks, and clouds of fish on a simple snorkel just offshore from the beach.

The island has three main beaches. Sunrise Beach (east coast) is the most beautiful — calm, shallow, and faced with a remarkable reef you can snorkel directly from shore. Sunset Beach (west coast) is the one for sundowners. Pattaya Beach in the south is the busiest, with most of the restaurants and bars along its “Walking Street.” The whole island takes about 40 minutes to cross on foot. There are no cars and no motorcycles — only the occasional bicycle.

Getting there: High-speed ferries run from Pak Bara pier (2 hours) or from Langkawi in Malaysia (45 minutes) during the season (November–May). Koh Lipe is genuinely remote — factor in a full day of travel from Bangkok. It’s worth every minute.

Koh Lanta — The Family-Friendly Alternative

Koh Lanta doesn’t have the name recognition of Phuket or the drama of Railay, which is precisely why it’s so good for families. The west coast has a series of long, gently sloping beaches with calm, clear water — Long Beach (Hat Khlong Dao) is the longest and most developed, with a wide sandy strip, safe swimming, and plenty of family-friendly restaurants and guesthouses along the road behind.

The further south you go on Koh Lanta’s west coast, the quieter it gets. Klong Nin Beach has a laid-back, slightly bohemian atmosphere — excellent beach bars, good sunsets, and none of the rowdiness of the more tourist-heavy spots further north. Bamboo Bay at the southern tip, inside the national park boundary, is stunning and almost empty. You need a motorbike or songthaew to get there.

Koh Lanta is also a great base for day trips: diving and snorkeling at nearby Koh Haa and Koh Rok, both of which rank among the best dive sites in the Andaman Sea. The island has a well-established diving scene with multiple reputable operators and is significantly cheaper than Phuket for comparable trips. Best for: families, digital nomads, anyone who wants to slow down and stay a week or more.

Ko Tao — World-Class Affordable Diving

Ko Tao is where half the world has learned to scuba dive. The island offers PADI Open Water certification courses at prices that make diving accessible to travelers who wouldn’t otherwise consider it — around $250–300 for a full 3–4 day course, compared to $400–600 in Australia or the Caribbean. The visibility is consistently good, the water temperature comfortable year-round, and the marine life excellent: whale sharks pass through seasonally, and the reefs around the island are among the healthiest in the Gulf.

Beyond diving, Ko Tao has a perfectly pleasant beach scene centered on Sairee Beach — a long, sandy strip on the west coast lined with guesthouses, restaurants, and dive shops. It’s more lively than Koh Lanta but far more manageable than Koh Samui. The bouldering scene at the southern end of the island has developed a dedicated following among rock climbers passing through.

How long to stay: If you’re doing a dive course, budget 4–5 days minimum. Non-divers can see Ko Tao’s highlights in 2–3 days comfortably. The ferry from Koh Samui takes about 1.5 hours and runs multiple times daily.

Koh Samui — Infrastructure and Nightlife

Koh Samui is Thailand’s second-largest island and the most developed beach destination in the Gulf — which is both its strength and its weakness. The strength: it has an international airport, a full range of accommodation from budget bungalows to ultra-luxury resorts, excellent hospitals, and the kind of infrastructure that takes the anxiety out of traveling with kids or older relatives. The weakness: the most popular beaches, especially Chaweng, can feel decidedly un-tropical during peak season.

Chaweng Beach is Samui’s party central — 6km of sand, lined with bars, clubs, and restaurants, and buzzing until 4am most nights during high season. It’s fun if that’s what you want. For something calmer, Bophut on the north coast has the charming Fisherman’s Village — restored wooden shophouses converted into boutique restaurants and galleries, with a quieter beach in front. Lipa Noi on the west coast catches the sunset and is genuinely peaceful.

Samui is also the best jumping-off point for exploring the Gulf islands — day trips to Ang Thong National Marine Park (the archipelago that inspired The Beach) are the island’s most popular excursion, and rightfully so. Go on a speedboat tour for maximum island access, or the slower catamaran for a more relaxed day.

Best Time to Visit Thailand’s Beaches

Thailand Beach Tips

• Reef-safe sunscreen only. Standard chemical sunscreens are damaging the coral reefs that make Thailand’s beaches worth visiting. Brands like Stream2Sea or Thrive work well in tropical conditions. Many shops in beach towns now stock them.
• Scooter safety. Renting a scooter is the easiest way to explore most Thai islands — and one of the most common sources of tourist injuries. Wear a helmet (always), go slow on unfamiliar roads, and check your travel insurance covers scooter riding before you get on one.
• Bargain on longtail fares, not dive prices. Haggle on boats, taxis, and market food. Do not haggle on scuba courses — cheap diving schools cut corners in ways that matter.
• Water safety: Rip currents are more common than most visitors realize, especially on the Andaman coast during monsoon shoulder months. Red flags mean stop. Don’t swim after dark. Jellyfish season varies by location — ask locals.
• Respect marine life. Don’t touch coral, don’t feed fish, don’t ride turtles. Thailand’s reefs are recovering — every snorkeler makes a difference.