The Similan Islands are one of Thailand's top-rated snorkeling and diving destinations and the hardest Phuket day trip to actually take. Mu Ko Similan National Park is closed from 15 May to 15 October 2026 – a five-month gate, far longer than any other closure on this coast. Even in season the boat leaves from Thap Lamu Pier near Khao Lak, roughly 100 km north of Phuket, which is what the 06:00 pickup is for.
The season is the whole planning problem
Mu Ko Similan National Park is closed to visitors from 15 May to 15 October 2026, on an order from Thailand's Department of National Parks, Wildlife and Plant Conservation. The same order covers Mu Ko Surin to the north. The closure runs through the southwest monsoon, both because the open Andaman is genuinely dangerous out there and because five uninterrupted months let the reef recover from a season of daily boat traffic.
Two practical consequences follow. First, more than a third of the year is simply unavailable – if you are in Phuket between mid-May and mid-October, there is no operator, price or workaround that gets you to the Similans, and a listing that appears bookable for those dates warrants an email before you pay. Second, the demand for a twelve-month destination is squeezed into seven months, which is why this is the most expensive of the standard Phuket boat days at around $117 rather than the $40–55 the closer islands cost.
The reopening date is 15 October, and the strongest window is December to March: calmest sea, best underwater visibility, and also the busiest and priciest. Late October and April are the quieter shoulders, with slightly less reliable conditions.
"From Phuket" means a drive to Khao Lak first
Every Similan day trip leaves from Thap Lamu Pier in Phang Nga province, about 5 km from Khao Lak and roughly 100 km north of Phuket. There is no Similan boat from a Phuket pier. What a Phuket-departing tour sells you is the road transfer as well as the boat.
That transfer is 1.5–2 hours each way by minivan, which is why hotel pickups run at about 06:00. From the pier it is another 1–1.5 hours by speedboat to the islands. Door to door you are looking at a day of roughly 12 hours from a Phuket hotel, against about 9 hours for the same trip booked from Khao Lak.
If you have any flexibility in your itinerary, this is the trip to take from Khao Lak rather than Phuket – you save around three hours of minivan. If Phuket is fixed, book a tour that includes the transfer rather than trying to reach Thap Lamu independently, and stay on Phuket's north end (Bang Tao, Nai Yang, Mai Khao) to shave 30–40 minutes off the pickup.
What "early-bird" actually buys you
Not an earlier arrival at the islands. The national park does not admit visitors before 08:00 and requires everyone off by 16:00, so no operator can put you on a beach at dawn.
What the early departure buys is your position in that eight-hour window. Boats that leave Thap Lamu first are at the front of the 08:00 queue, get their snorkel stop before a dozen other hulls arrive over it, and reach Donald Duck Bay while the beach is still empty enough to photograph. Boats that leave late spend the good morning light on the water and arrive into a crowd.
On a trip where the park's own clock caps the day at eight hours regardless of what you pay, being first through the gate is a real product difference rather than a marketing line.
What the day covers
The Similans are eleven granite islands about 60 km off the Phang Nga coast, and a day trip reaches two or three of them.
Island 8, Koh Similan, is the headline stop. It holds Donald Duck Bay – named for a granite boulder on the ridge above it – and the short, steep scramble up to the Sail Rock viewpoint that produces the photograph the trip is sold on. Island 4, Koh Miang, is the park headquarters, with the beaches most tours use for the lunch stop and a couple of short walking trails. Snorkel stops are usually worked in around Island 9 and the shallow reef edges near the anchorages.
The reason to come is under the surface rather than on it. These are granite islands, not limestone – huge rounded boulders continuing below the waterline into swim-through formations, with visibility in the dry season that is on a different scale from the Phi Phi or Phang Nga stops closer to Phuket. If snorkeling is why you booked a boat day at all, this is the one to spend the money on. If you want beaches, lunch and a manageable schedule, one of the closer trips serves you better for a third of the price.
Where it fits in a Phuket week
This is the specialist day among Phuket's six water days, and it is the only one with a five-month gate on it. South, the Phi Phi Islands day trip is the high-volume beaches-and-snorkeling standard, with its own two-month Maya Bay closure each August and September. East, Phang Nga Bay is sold three times over – the James Bond Island longtail tour by day, a luxury sunset cruise in the evening light, and a bioluminescent plankton night canoe after dark. If it is diving rather than snorkeling you are after and the season does not line up, Discover Scuba Diving at Racha Yai runs every month of the year and is often at its best exactly when this park is shut.
Take Similan if your dates fall in the open season and the water is the point; take one of the others if they do not. Between 15 October and mid-May, the early-bird tour in the box above is the version worth booking from Phuket – the pickup time is the whole advantage, and December to March dates go early.
For the nights either side, Phuket's northern beaches cut the most off that 06:00 drive: our guides to the island's private pool villas, swim-up rooms and beachfront resorts cover which resorts sit where.
FAQ – Similan Islands day trips from Phuket
Images: Mathias Krumbholz / Wikimedia Commons / CC BY-SA 3.0
