Similan Islands Reopening 2026: Opening Date & How to Book Early

Quick Answer: Mu Ko Similan National Park reopens on 15 October 2026 and stays open until around 15 May 2027. Visitor numbers are capped every day, boats fill up from the first week, and the park is closed for five months on either side. If you are in Thailand this season, book the day trip early.

If you only do one sea trip in Thailand, make it this one. The Similan Islands Snorkeling Day Trip From Phuket runs from the day the park opens, with hotel pickup anywhere in Phuket.

Similan Islands 2026-27 Season Dates

Mark the two dates and work around them.

• Opens 15 October 2026. The park reopens after the southwest monsoon, with everything – reefs, beaches, moorings – fresh from five months of recovery.
• Closes around 15 May 2027. The exact date moves with the weather, and the park can shut earlier if the monsoon arrives early.
• Closed 16 May to 14 October every year, by order of the Department of National Parks. There is no way to visit in those months (as of 2026). 

Those five closed months are why the Similans still look the way they do. No boats, no swimmers, no pressure on the reef – then one morning in October the park opens and the water is as clear as it gets all year.

Why the Similans Are a Must-Visit in Thailand

• The water: Visibility is measured in tens of metres rather than a few – around 30 metres on a good day, by the operator’s own figure. You float on the surface and see the sand below in detail.
• The granite: Not limestone like Phang Nga Bay, but enormous rounded granite boulders stacked and balanced above white sand – they look like nowhere else in the country. Sail Rock, above Donald Duck Bay, is the one on every postcard.
• The beaches: Powder-white sand, almost no development, water that runs from clear to pale blue to deep blue in thirty metres.
• Marine life: Reef fish in quantity, healthy hard coral, and a real chance of turtles – the operator lists sea turtles and dolphins among the possibilities, which is the right word for wild animals. Nobody can promise them; plenty of trips see them. 
• The reputation: Skin Diver Magazine has named the Similans among the world’s best diving destinations, and the park has held that standing for decades.

Why You Should Book Early

This is not marketing urgency. It is how the park is run

• There is a hard daily cap. The park admits a limited number of visitors per day – 3,325 under the current notice – and when the day’s allocation is gone, it is gone. Operators work within that number.
• The opening weeks fill fast. Mid-October carries five months of pent-up demand, and the first trips of the season are the ones people have been waiting for.
• December to February is the peak. Christmas, New Year and Chinese New Year land inside the calmest stretch of the season. Those weeks book up furthest ahead.
• Booking early lets you pick your day. Book on arrival and you take what is left; book ahead, and you can place the trip early in your stay – which matters, because a rough day gets cancelled and you want room to reschedule.
• You get the boat you want. Speedboat, catamaran or the double-deck catamaran: the choice is only yours if you book before the popular option is full. 

Lock the date in and build the rest of the trip around it: Similan Islands Snorkeling Day Trip From Phuket.

Best Time Within the Season

Every part of the season has an argument for it.

• October to November. The reefs are at their freshest after the closure, with fewer boats than peak, and the greenest the surrounding coast ever looks. The best-value window of the year.
• December to February. The flattest sea and the most reliable sailing days. This is the postcard version, and it is busy for good reason.
• March to April. Warm water, long clear days and some of the best visibility of the whole season, right up to the closing date in May.

In short: come early for value and space, mid-season for certainty, late for the water.

What Your Day Trip Looks Like

A long, full day that moves. Early pickup from your Phuket hotel, road transfer north to Thap Lamu pier, breakfast and gear fitting, then the crossing. On the islands, you snorkel at Ko Miang, Ko Pa Yu and Bangu Island – Christmas Point – then land on Similan Island for Donald Duck Bay and the short climb to Sail Rock. Thai food, fruit, drinks, gear, an English-speaking guide and accident insurance are included; the park fee is paid separately. Ten hours door to door, ages 2 to 80, thirty people maximum.
Three boats to choose from: the speedboat for the fastest crossing and most time on the islands, the catamaran for a smoother, steadier ride, and the double-deck catamaran for the most space and the best upper-deck views. Our full day trip walkthrough goes through the programme stop by stop. 

Staying up the coast rather than on Phuket? The Similan Islands Tour From Khao Lak leaves from the same pier with a much shorter road transfer at both ends.

Park Rules to Know Before You Go

• Entrance fee: around 400 baht for foreign adults and 200 baht for children, paid in cash at the park and not included in tour prices. Rates are set by the national park department and can change, so carry a little extra (as of 2026). 
• Daily cap: 3,325 visitors, which is why booked trips do not simply expand on a busy morning. 
• Hours: 08:00 to 16:00. Every day the boat has to be out of the park by four, which is why the day starts so early.
• No overnight stays. Camping and park accommodation on the islands ended some years ago.
• Ko Tachai is closed to landings and has been since 2016, to let it recover.
• Don’t touch the coral, feed the fish, or take anything home. Shells, coral, and sand all stay. Reef-safe sunscreen, or a rash guard instead.
• Bring ID. A copy of your passport, or a photo of it on your phone, is needed at check-in.
• Not advisable if you are pregnant or have heart, blood pressure, or back and joint conditions.

How to Book in Three Steps

1. Choose your date: Aim for early in your trip so you have flexibility if weather conditions change. 
2. Choose your boat: Options range from speedboats for faster travel to catamarans or double-deck boats for extra space and comfort. 
3. Reserve your spot: Secure your ticket online in advance. Most options include simple confirmation and flexible cancellation policies up to 24 hours before departure. 

Still weighing the Similans against the other marine park up the coast? Our comparison of the two sets them side by side, and the Surin day trip guide covers that alternative in full.

FAQ 

Don’t Leave Thailand Without Seeing the Similans

Seven months open, five months shut, a hard cap on every single day, and no second chance until next October. If your trip overlaps with the season, this is the day to book first and plan the rest around. 

Similan Islands Snorkeling Day Trip From Phuket – hotel pickup across Phuket, your choice of boat, gear, lunch, and guide included, free cancellation up to 24 hours before. Pick the date, and the clearest water in Thailand is waiting on the other side of 15 October.