Sailing in the Gulf of Thailand: Koh Samui, Koh Phangan & Koh Tao

Sailing in the Samui Archipelago: routes, seasonal winds and practicalities

The Samui archipelago—centred on Koh Samui, Koh Phangan and Koh Tao—offers compact passages, reef-fringed anchorages and a genuine sense of island-hopping adventure. When sailing in Thailand, conditions vary markedly with the monsoon, so success hinges on understanding when each coastline comes into its own. Expect mostly line-of-sight navigation by day, abundant snorkelling in clear water, and nights at anchor rather than in marinas.

This guide sets out realistic itineraries, seasonal wind behaviour, where to anchor in each phase of the year, and what you need to know to charter safely and confidently. If you plan around the monsoon and arrive early to choose your anchorage, you will be rewarded with calm nights, clear water and memorable hikes to viewpoints between swims.

Quick links

• Sailing the Samui Archipelago: routes, seasonal winds and practicalities
• Why Sail in Gulf of Thailand: Koh Samui, Koh Phangan & Koh Tao?
• Itineraries
• When to go
• Wind and weather
• Getting there
• Chartering
• Licences and formalities
• Anchorages and marinas
• FAQs
• References

Why Sail in Gulf of Thailand: Koh Samui, Koh Phangan & Koh Tao?

For many skippers, the appeal lies in short hops with big contrasts. Within a day’s sail you can move from the limestone domes and emerald lagoons of Ang Thong National Marine Park to the palm-fringed bays of Koh Phangan and the coral gardens of Koh Tao. The distances are forgiving, yet the sailing is never dull: sea breezes build reliably in settled months, and there is nearly always a lee to be found if you match your plan to the season.

The archipelago is also decidedly practical. Deepwater ferries, good provisioning on Koh Samui, and numerous all-weather anchor options make this an approachable destination if you are new to tropical sailing. There are few formal marinas, but that is the point: you will anchor beneath jungle ridgelines, pick up park moorings over coral, and time your moves around the monsoon to keep life comfortable on board.

Finally, the water is a major draw. On clear days, Koh Tao’s reefs are superb for easy snorkelling straight from the transom, while Ang Thong’s moorings position you close to iconic viewpoints and caves. If you value wildlife, warm seas and compact passages over marina-hopping, this corner of the Gulf of Thailand delivers.

Itineraries

Below are two tried-and-tested routes that balance sailing time with time at anchor. Use them as frameworks and adapt to the season: in the North-east monsoon you will prefer west and south coasts; in the South-west monsoon, north and east coasts shine. Always plan daylight arrivals into reefed bays.

7-day circuit: Samui, Ang Thong, Phangan and Tao

A relaxed week that samples the best of the archipelago: a shakedown on Samui’s north, limestone scenery in Ang Thong, broad sandy bays on Koh Phangan and clear-water snorkelling on Koh Tao. Distances are modest—typically 10–25 nautical miles—so you can sail in the breeze, swim at lunch and still be anchored early. Adjust your overnight bays to the monsoon: choose west/south-facing lee shores in the NE monsoon, and east/north-facing lee shores in the SW monsoon.

Day 1 — Koh Samui (Bo Phut) shakedown

Join the boat, provision and complete briefings. Conduct a short shakedown along Samui’s north coast to test systems and settle the crew. Bo Phut offers easy anchoring in settled weather with ready access to services around Fisherman’s Village; Bang Rak (Big Buddha Bay) is a practical alternative. Keep an eye on fast local traffic and ferry wash.

Day 2 — Samui to Ang Thong National Marine Park

Reach or motor-sail WNW to the limestone islets of Ang Thong. Pick up a park mooring off the headquarters at Koh Wua Talap, then hike the viewpoint in the late afternoon for sweeping lagoon vistas. If conditions allow, visit Koh Mae Ko’s Emerald Lake by dinghy in settled hours. Expect katabatic gusts funnelling off the ridges after sunset—set a bridle.

Day 3 — Explore Ang Thong, then to Koh Phangan

Snorkel in the morning at one of the marked sites while the light is high, then shape an easterly course for Koh Phangan. In the NE monsoon favour the west coast (Haad Yao, Haad Salad) for reliable sand and shelter; in the SW monsoon, the NE bays (Thong Nai Pan) shine with smooth water and scenic surrounds. Arrive early to pick out sand patches between coral heads.

Day 4 — Koh Phangan to Koh Tao

A satisfying open-water leg to Koh Tao. Make a tidy departure window to avoid wind-over-tide steep chop mid-channel. Arrive before mid-afternoon to secure a mooring or sand patch off Mae Haad or Sairee on the west side in settled conditions. Keep clear of the ferry track when selecting your spot.

Day 5 — Koh Tao snorkel circuit

Work around Koh Tao’s bays by daylight, mindful of coral shelves and dive moorings. Use the lee side for the day’s wind direction—Aow Leuk and Shark Bay are glorious in lighter or SW phases; Mango Bay rewards calm mornings with clear water. Inspect any borrowed mooring before committing.

Day 6 — Return to Koh Phangan

Sail SSW back to Phangan. Choose a bay to suit the season: Thong Nai Pan in the SW monsoon; west-coast anchorages in the NE monsoon. If swell wraps in, shift a headland or two until you find smooth water. Aim to arrive early for good holding in sand and a relaxed evening ashore.

Day 7 — Koh Phangan to south or north Samui

A short final leg tailored to conditions. In the NE monsoon, favour Samui’s south or west coasts (Bang Kao, Thong Krut); in the SW monsoon, the north and east are typically calmer. Return fuel in good time and prepare for hand-back with decks rinsed and gear stowed.

4-day mini-cruise: Samui, Ang Thong and Phangan

Perfect for a long weekend or first charter in the tropics. This compact loop keeps passages short, focuses on park scenery and gives you a flavour of Koh Phangan’s bays. Prioritise early starts, daylight arrivals and flexible anchorage choices to match the breeze and swell.

Day 1 — Samui north coast

Embark at Bo Phut or Bang Rak. Take a short sail to settle the crew and systems, check reefing lines and confirm the anchor sets well in local sand. Shore access here is straightforward for any last-minute provisions.

Day 2 — Ang Thong National Marine Park

Make the most of the morning to reach the park in calmer seas. Pick up a marked mooring and explore ashore between swims. Plan dinghy runs around slack water for easier landings at cave beaches and stairways.

Day 3 — To Koh Phangan

A relaxed beam reach brings you to Phangan. Choose shelter to suit the season and swell; the west coast is dependable in NE phases, while the NE coves are serene in the SW monsoon. Enjoy a sunset swim and keep an anchor watch alarm set just in case of katabatic gusts.

Day 4 — Back to Samui

Short hop back to Samui for checkout. Time your arrival for fuel and formalities in daylight, allowing for ferry traffic around Na Thon. Rig fenders and lines early and have paperwork and receipts ready for a smooth handover.

When to go

Two distinct monsoon patterns shape the season.

November to January (Northeast monsoon): Expect prevailing NE–E winds, at times fresh, with the heaviest rainfall typically in November. The east and north coasts of Samui, Phangan and Tao can be exposed, while western and southern anchorages—plus Ang Thong’s more enclosed moorings—are favoured. Seas can be lumpy in the channels during strong surges; plan shorter legs and conservative arrivals.

February to April (inter-monsoon/early dry): Often the most settled period. Winds are lighter and more variable, with reliable daytime sea breezes and clearer water for snorkelling. Hot days and gentle overnights suit exploration on all coasts with careful attention to local wind trends.

May to September (Southwest monsoon): Generally gentler in the Gulf than on Thailand’s Andaman side. SW–S winds bring occasional squalls but many fine, sailable days. The east and north coasts become the lee; Koh Tao’s west can be pleasant in lighter spells, while Phangan’s NE bays (e.g., Thong Nai Pan) are attractive.

October (transition): Highly changeable with thunderstorms and rising rainfall. Flexible plans and extra caution with anchor choices are advisable.

In practice, the shoulder months on either side of the monsoons can deliver great sailing if you keep plans loose and choose lee shores day by day. Regardless of month, arrive early to evaluate swell in each bay, and have a secondary option a short sail away.

Wind and weather

Winds: In settled months, a diurnal pattern is common: light mornings, then an onshore sea breeze building to 8–15 knots by early afternoon, easing after sunset. During monsoonal surges, the gradient wind dominates—NE in November–January and SW in May–September—with brief squalls capable of 25–35‑knot gusts. Reef early if anvil clouds stack on the horizon and keep mainsail controls to hand.

Seas and swell: Short, steep seas kick up quickly in the channels, especially against tide. In NE spells, east-facing bays can be rolly; in SW spells, west-facing shores feel more exposed. Within Ang Thong, high islands temper the sea state but katabatic gusts off the ridges are common—allow swinging room and use a bridle.

Visibility and humidity: Hazy skies are typical late in the dry season; showers clear visibility quickly. Tropical humidity is persistent—plan ventilation at anchor using wind scoops and insect screens.

Tides and currents: Tidal range is modest (roughly 0.5–2 m) and currents are generally weak, though localised sets occur between headlands and islets. Many bays shoal gradually to coral shelves; identify clear sand before committing the hook. Night entries are not recommended due to reefs, unlit fishing gear and small-boat traffic.

Weather information: Local forecasts are broadcast in Thai; most crews rely on GRIBs and regional marine bulletins. Mobile coverage is good around the main islands but patchier deeper in Ang Thong.

Good seamanship goes a long way here: start passages early before sea breeze peaks, reef on the conservative side ahead of squalls, and angle for lee shores to make lunch stops pleasant. If swell builds, shifting one or two headlands can transform comfort at anchor.

Getting there

By air: Koh Samui (USM) has frequent domestic flights from Bangkok (BKK/DMK) and seasonal regional connections (e.g., Singapore, Kuala Lumpur). Taxis and pre-arranged transfers cover the short hop to common charter pick-up points around Bo Phut or Bang Rak. Flight schedules fluctuate with season; allow generous buffer time if your crew is connecting internationally.

By ferry: High-speed ferries run from Surat Thani’s Donsak piers to Samui (Na Thon, Lipa Noi) and to Phangan (Thong Sala). Routes from Chumphon and Surat Thani connect to Koh Tao (Mae Haad). Sea state, tides and demand can affect schedules—build contingency into embarkation and checkout days.

Provisions and spares: Samui has large supermarkets and chandleries near the north and west coasts. Diesel is available at Na Thon and via fuel barges or dockside services arranged by your operator. Water is commonly delivered by dock truck or by jerrycan; plan top-ups at changeovers. Specialist items (spares, charging cables, snorkel gear) are easiest to source on Samui—stock up before you head to Ang Thong or Koh Tao.

Chartering

Charter styles: The region is geared towards crewed and skippered catamarans, with a smaller pool of bareboats than Phuket. Catamarans offer shallow drafts and generous living space for warm, at-anchor life. Monohulls are available but less common.

Bases and handovers: Most operators stage embarkation off Samui’s north coast (Bo Phut/Bang Rak). There are no full-service marinas; you will typically take a tender or support boat to a mooring or anchorage for handover. Briefings focus on reef awareness, seasonal anchor choice and local traffic. Ask for waypoints to preferred fuel docks, park moorings and safe dinghy landing spots.

Itineraries: In settled weather, a week comfortably takes in Ang Thong, Phangan and Tao with time to linger. In stronger NE spells, consider a western loop—Ang Thong and Samui’s south and west coasts—leaving Koh Tao for lighter days. Build itineraries around lee shores rather than fixed dates and keep daily runs short enough to allow early arrivals.

Support and services: Divers’ moorings are widespread off Koh Tao; many are private—seek permission via your operator and always inspect lines. Park moorings in Ang Thong simplify overnights but can be busy—arrive early. Most operators can arrange kayak/SUPs, fishing gear (outside protected zones) and rendezvous-diving. Confirm safety gear (jackets, tethers, first aid, VHF) and ensure your tender has a proper anchor and an anchor light for night-time visibility.

Costs and fees: Expect national park fees in Ang Thong, payable in cash to rangers who visit by boat. Some bays levy mooring or landing fees. Carry small denominations and keep receipts on board. Budget for fuel runs, water deliveries and optional equipment hire.

Licences and formalities

Bareboat certification: Operators typically require evidence of skipper competency such as an ICC, RYA Day Skipper (Practical) or ASA 104 Bareboat Cruising, plus recent tidal and anchoring experience. A VHF/SRC certificate is commonly requested. Logbook evidence of prior passages strengthens applications. If in doubt, opt for a local skipper for the first days.

Crewed charters: No formal qualifications are needed if you hire a professional skipper; you remain responsible for conduct and costs. Skippers know where to find lee anchorages in each phase of the monsoon and can accelerate your learning curve.

Documents and deposits: Bring passports for all crew, booking confirmations, and payment cards for security deposits. Operators will collect crew lists in advance. Ensure travel insurance covers sailing as a named activity, including dinghy use and snorkelling.

Private yachts (arrivals): If you are cruising in on your own vessel, clear in at a designated Port of Entry (e.g., Koh Samui/Na Thon or Surat Thani). You will deal with the Marine Department, Immigration and Customs. Carry ship’s papers, crew passports and a crew list. Thailand issues a Temporary Import for the yacht on arrival; keep copies aboard. Always check current rules before you sail. Within Ang Thong, observe park regulations: no anchoring on coral, no fishing, and use designated moorings where provided.

Anchorages and marinas

Overview: There are no conventional marinas in the Samui archipelago. You will anchor or pick up moorings most nights. Holding is generally in sand with coral patches; identify clear sand before dropping and reverse firmly to set. Plan all entries in daylight—reefs, fishing stakes and unlit moorings are common.

Koh Samui

North coast (Bo Phut, Bang Rak)

Convenient for handovers and shore access, with supermarkets and services close by. Good in the SW monsoon and light conditions, but can be rolly in strong NE flows. Expect depths of 3–6 m over sand and regular wake from ferries and speedboats—anchor well clear and display an anchor light.

West coast (Na Thon, Lipa Noi)

Practical stops for fuel and supplies with a reliable lee in the NE monsoon. Wake from ferries is frequent near piers; keep clear of fairways and monitor traffic on approach. The holding is generally sound in sand; allow room for swinging with passing wash.

South coast (Bang Kao, Thong Krut)

Spacious sandy bays with useful protection in the NE monsoon. Shelves shoal gradually with isolated coral heads—post a bow lookout in bright overhead light for entry and exit. Shore facilities are simpler but peaceful.

East coast (Chaweng, Lamai)

Pretty, palm-backed beaches but exposed in the NE monsoon. Feasible in lighter spells and during the SW monsoon when often in the lee. Fringing reefs demand accurate entry in good light and settled seas; avoid late arrivals.

Koh Phangan

West coast (Haad Yao, Haad Salad)

Dependable in the NE monsoon with sandy bottoms and good holding. Expect gusts off the hills and fringing coral shelves—pick a sand patch and back down firmly to set the hook.

North coast (Chaloklum Bay)

A large, easy bay with services ashore and good access to the island’s interior. Comfortable in NE spells; open to summer westerlies and any northerly swell. Anchor towards the eastern side for a little extra shelter if swell wraps in.

Northeast (Thong Nai Pan)

Twin coves with excellent sand patches and scenic surrounds. Best in the SW monsoon and settled periods. Can be exposed in fresh NE winds; if it becomes bouncy, shift to a west-coast bay.

South (Haad Rin/Leela)

Attractive beaches with lively shore scenes, but open to swell and frequent small-boat traffic. Not ideal in strong wind phases or around event periods—expect noise and wash.

Koh Tao

West side (Mae Haad, Sairee)

Handy for arrivals with moorings often available. Best in settled weather; open to NE surge. Keep clear of ferry approaches at Mae Haad and always check the condition of any mooring.

South and east (Aow Leuk, Shark Bay, Tanote)

Superb snorkelling with living coral shelves. Better in light or SW phases. Many moorings belong to dive operators—do not assume maintenance and avoid leaving the boat unattended in fresh breezes.

North (Mango Bay)

Clear water and sand patches reward calm or SW conditions; avoid in fresh northerlies when swell can funnel straight in. Arrive with the sun high to read the bottom clearly.

Ang Thong National Marine Park

Moorings are set in popular spots such as Koh Wua Talap and Koh Mae Ko. Anchoring on coral is prohibited. Rangers collect fees afloat—carry cash. Expect strong gusts around cliffed islets and limited swinging space; arrive early, rig a bridle and keep chafe gear handy.

Practical tips

• Depth and coral: Approach with the sun behind you where possible and use a bow lookout. In marginal light, wait offshore.
• Night: Avoid night passages due to unlit fishing gear and small-boat traffic.
• Environmental care: Use moorings over coral, avoid anchoring on reef, and take all rubbish back to main islands.
• Dinghy landings: Many beaches are shallow; time landings between sets and lift outboards in surf.

With good light and unhurried arrivals, navigation is straightforward. If in doubt, pause offshore, review satellite imagery and ask neighbouring skippers about current conditions before committing to a tight entrance.

FAQs

References

• https://www.cruiserswiki.org/wiki/Gulf_of_Thailand:_Koh_Samui,_Koh_Phanngan_%26_Koh_Tao
• https://www.tmd.go.th/en/
• https://www.hydro.navy.mi.th/index.php/en/
• https://www.thainationalparks.com/ang-thong-national-marine-park
• https://www.samuiairport.com/
• https://www.seatranferry.com/