The Similan and Surin Islands reopen to visitors on 15 October 2026 for the 2026–27 season, and stay open until around 15 May 2027. Both are marine national parks run by Thailand's Department of National Parks, and both follow the same annual rhythm: open through the dry months, closed for the full southwest monsoon. In practice you can visit from mid-October to mid-May and not at all in between. The department confirms exact dates each year, so check them again if your whole trip is built around reopening week.
Similan & Surin 2026–27 at a glance
| Similan Islands | Surin Islands | |
|---|---|---|
| Open season | 15 Oct 2026 – ~15 May 2027 | 15 Oct 2026 – ~15 May 2027 |
| Closed | ~15 May – 14 Oct | ~15 May – 14 Oct |
| Daily visiting hours (reported) | 08:00 – 16:00 | 08:30 – 16:30 |
| Park fee, foreign adult | ฿500 | ฿500 |
| Park fee, child 3–14 | ฿250 | ฿250 |
| How to pay | E-ticket rolling out; bring cash | E-ticket rolling out; bring cash |
Children under three enter free. Day-trip and liveaboard operators usually build the park fee into their price or collect it on the boat, so check what yours includes before you hand over cash twice.
Why the parks close for five months
The closure is part weather, part deliberate conservation. The southwest monsoon (roughly May to October) brings the roughest seas of the year to the outer Andaman. The Similans and Surins sit a long way offshore in open water, and monsoon swell makes that crossing genuinely hazardous for day boats. The five-month pause also gives the reefs a real rest: coral regenerates, fish stocks rebuild in water nobody is motoring through, and turtles nest undisturbed. It's the same thinking behind the annual Maya Bay closure, applied to whole archipelagos. After reopening, the park sets a daily visitor cap each season so one high season doesn't undo the recovery.
Practical notes for the reopening weeks
- Bring cash. The national parks department launched an e-ticket system for its marine parks in October 2025, but the rollout is phased and cash is still what changes hands at most piers. Small notes make it easier.
- The first sailings of the season are the most exposed to weather. A late burst of monsoon swell in mid to late October can cancel or shorten trips. If the Similans are the highlight of your holiday, book for November to April, when the seas are calmest and visibility is at its best.
- Koh Tachai is a separate case. The northern island has been closed to visitors since 2016 to let its reefs recover, and no reopening date has been announced. Be wary of any itinerary that lists it, and check before you book. Our Tachai Island guide has the background.
- Mind the hours. Landings and snorkel stops run inside the park's daily window, so the very early or late departures some boats advertise are mostly time spent crossing.
Why we don't run Similan day trips from Phuket
Simba Sea Trips doesn't sell a Similan or Surin day tour from Phuket. That's a deliberate safety decision, not a gap in the brochure. I've been on the water most of my life and running boats commercially in Phuket since 2014, and I set the marine SOPs every Simba departure follows. The numbers on that route have never worked for us. The Similans are a long way out across open sea. If a speedboat loses an engine out there, which really does happen in marine operations, the trip home turns into a five-to-six-hour crawl that lands passengers back at the dock after dark in worsening conditions. Some operators accept that risk with a full boat. We won't.
If the Similans are a must, base yourself in Khao Lak. It's the closest mainland departure point and cuts the open-water crossing down a lot. Go with your eyes open, though: most Khao Lak Similan boats are high-volume operations carrying 30 or more passengers, a very different day from a small-group trip. Our Similan Islands from Phuket page goes through the transit times in detail.
What we run instead from Boat Lagoon
If what you're really after is clear water, dramatic rock and great snorkelling, rather than the Similan name itself, these trips deliver it year-round. All of them leave from our base at Soho Pool Club, Boat Lagoon Marina, carry a maximum of 18 adults, and have all-inclusive prices:
- Phi Phi Sunrise Tour. Watch the sunrise at sea on the way out, then reach Maya Bay and Pileh Lagoon before the day-tripper crowds.
- Phang Nga Bay & James Bond Island. Limestone karsts, sea caves and the hongs of Koh Hong.
- Coral Delight Private Charter. Quieter southern-Phuket snorkel sites, with lunch back at Soho Pool Club.
- Krabi Private Charter. Railay, Chicken Island and the Hong lagoon, about 50 km by sea instead of 180 km by road.
More on the Similans
To learn what the islands are actually like, start with the full Similan Islands guide and the Similan Islands destination page. For transfers and piers, see getting to the Similan Islands. If your holiday falls inside the closure window, our guide to which Phuket islands stay open in monsoon season covers the alternatives. Heading further north? Our Surin Islands guide covers getting there from Khuraburi, the Moken village and the best snorkelling.
