Similan Islands 6-Day Liveaboard 2026/2027: Manta Rays, Whale Sharks & Richelieu Rock

Why the Similans top every Andaman bucket list

Closed for half the year and protected as a national park, the Similan archipelago is Thailand's diving crown jewel. Granite boulders the size of cathedrals form sculpted underwater landscapes; sheer walls drop into deep blue water; and the migratory corridor connecting Koh Bon, Koh Tachai and Richelieu Rock funnels pelagics straight onto the reefs.

Day-trip operators reach the Similans, but they pay a heavy price: half the day is lost to transit, and the best big-animal sites — Koh Tachai Pinnacle and Richelieu Rock — are simply too far for a return run. A liveaboard puts you on site at dawn, dives the same reef while day boats are still in Khao Lak harbour, and rewards every guest with the rare luxury of an empty Richelieu Rock.

On board the MV Sawasdee Fasai

Our partner vessel for the 2026/2027 season is the MV Sawasdee Fasai — a purpose-built dive yacht with a relaxed, family atmosphere. The boat carries a small group of divers across three cabin classes: shared twin, standard double with private bathroom, and deluxe master cabin with panoramic windows.

Two sun decks, a covered lounge, an air-conditioned dining saloon and a generous dive platform mean you'll never feel crowded. Tanks are filled at your station; rinse buckets and camera tables are set up before you surface; and a freshwater shower greets you on the swim deck after every dive.

• Shared cabin — twin berths, shared bathroom, the best-value option for solo divers.
• Standard cabin — private bathroom, double or twin configuration, the most popular choice for couples and friends.
• Deluxe cabin — large windows, king bed, private bathroom with hot shower — the quietest cabin on board.

The dive sites: from Elephant Head to Richelieu Rock

The cruise covers the entire northern Andaman dive corridor — nine of the most iconic sites in Asia, each chosen for its own personality and a complementary mix of topography, current and macro life.

• Elephant Head Rock (Similan #8) — a maze of granite boulders, swim-throughs and resident schools of yellow snapper. The site of choice for the trip's signature wide-angle photographs.
• East of Eden & Christmas Point — vivid soft coral slopes, leopard sharks resting on the sand, hawksbill turtles feeding in the shallows.
• Koh Bon — a long ridge plunging to 40 m, the most reliable manta ray cleaning station in Thailand.
• Koh Tachai Pinnacle — a submerged seamount swept by current, with schooling barracudas, giant trevally and frequent whale-shark passes.
• Richelieu Rock — Jacques Cousteau's favourite dive in Thailand. A horseshoe of purple soft coral, schooling chevron barracuda and the season's best chance of a whale-shark encounter.
• Boonsung wreck (optional add-on) — a tin-dredger now home to lionfish, ghost pipefish and harlequin shrimp; a perfect last-day macro dive.

Marine life: what you can realistically expect

The Similan corridor is one of the few places in Asia where a single liveaboard can deliver a full pelagic spread, world-class macro and dramatic reef topography in the same week. Manta rays — both reef and oceanic — are sighted on more than 70% of February–April trips at Koh Bon and Koh Tachai. Whale sharks pass through Richelieu Rock and Koh Tachai roughly one trip in three during the same window.

On the reefs, expect schooling chevron barracuda, big-eye trevally, blue-fin trevally, dogtooth tuna and a quiet population of leopard sharks at Elephant Head and Christmas Point. Macro hunters get tigertail seahorses, harlequin shrimp, ornate ghost pipefish and the durban dancing shrimp that gave Richelieu Rock its first underwater fame.

The 6-day, 5-night itinerary

Every package is private — your group, your boat, your French-speaking guide. The structure below is the standard programme; dive sites are adjusted daily for conditions, currents and tidal windows.

• Day 1 — Arrival: meet at Bangkok airport, domestic flight to Phuket, hotel check-in and welcome briefing. Free evening in Phuket Town to explore the Sino-Portuguese quarter and the night market.
• Day 2 — Boarding & 4 dives: morning transfer to Khao Lak pier, board the MV Sawasdee Fasai, sail to the Similans. Four dives including a sunset and a night dive. Dinner aboard.
• Day 3 — 4 dives at the Similans & Koh Bon: granite reefs in the morning, Koh Bon ridge in the afternoon for manta encounters, night dive at Stonehenge.
• Day 4 — 4 dives at Koh Bon, Koh Tachai & Richelieu Rock: the headline day. Two dives at Richelieu Rock for the chance of a whale-shark pass, two pelagic dives on Koh Tachai Pinnacle.
• Day 5 — 2 dives, Koh Bon Pinnacle then return: morning dive on the pinnacle, second dive on a Similan reef, then sail back to Khao Lak. Transfer to your Phuket hotel for the night.
• Day 6 — Departure: transfer to Phuket airport, domestic flight to Bangkok, onward taxi to Pattaya. End of services.

What's included in the package

Everything on this itinerary is booked and coordinated by Thailand Diving as a fully private service — no shared minibuses, no surprise add-ons at the dive centre.

• All transfers (Bangkok ↔ airports, Bangkok–Phuket domestic flights both ways, taxi and pier transfers)
• 1 night in a Phuket hotel before boarding + 1 night after disembarking
• 5 days / 4 nights on board the MV Sawasdee Fasai in the cabin class of your choice
• Up to 18 dives — tanks, weights, divemaster and dive guide included
• Full board on the boat: breakfast, lunch, dinner, snacks and soft drinks
• A dedicated French-speaking instructor for the whole trip
• National park fees, port fees and harbour taxes

How to reserve

Cabins are released six months in advance and the February–April manta window typically sells out by November. To secure your dates, a 50% deposit confirms the reservation; the balance is due 30 days before departure.

Payment is by international bank transfer (Kasikorn Bank, Thailand) or via Wise — both sets of bank details are sent on enquiry. Full programme, deck plan and live availability are on the dedicated season page below.