When are the Similan Islands open — do they really close?
Yes, they really close. Mu Ko Similan National Park shuts every year during the southwest monsoon and is generally open only from around mid-October to mid-May (roughly 15 October to 15 May). It closes for the rest of the year because the seas are rough and dangerous, and to let the reefs recover. During the closure all boat tours stop. The exact opening and closing dates shift slightly each year — Thailand's national park department announces them annually. Before you plan, always check the latest opening dates, and note that daily visitor numbers are capped, so some periods need advance booking.
What's the difference between a Similan day trip and a liveaboard, and which should I choose?
A day trip is a there-and-back run by speedboat from a pier near Khao Lak and Thap Lamu in Phang Nga. It suits people who want to snorkel and walk the beaches — expect roughly 2,500–4,000 THB per person including transfers from Phuket, lunch, and fees, but it's a long, tiring day with a lengthy speedboat ride. A liveaboard is a boat you sleep on for 2–4 nights, built for certified SCUBA divers who want several dives a day and access to far sites like Koh Bon, Koh Tachai, and Richelieu Rock. Liveaboards start in the tens of thousands of baht. If you only want to snorkel, a day trip is enough. If you're serious about diving, choose a liveaboard.
How far are the Similans from Phuket and how long does it take?
Reasonably far. The Similans sit off the Phang Nga coast — they are not a close-to-Phuket island like Phi Phi or Phang Nga Bay. Most day trips collect you from your Phuket hotel before dawn, around 5–6 am, drive north to a pier near Khao Lak and Thap Lamu in about 1.5–2 hours, then transfer to a speedboat for roughly another 1.5 hours. All in, the one-way journey from Phuket is usually over three hours, so set aside the whole day. If you'd rather not sit in a van for so long, staying in Khao Lak puts you much closer to the pier than Phuket.
Will the speedboat to the Similans make me seasick, and how do I prepare?
Honestly, the speedboat runs over an hour across open sea and pounds through swells, so if you're prone to seasickness there's a real chance you'll feel ill — especially early season (Oct–Nov) or late season (Apr–May) when the sea is still choppy. Take a motion-sickness tablet 30 minutes to an hour before boarding, sit in the middle of the boat where it rolls least, keep your eyes on the horizon, and carry a bag just in case. If you suffer badly, a liveaboard on a larger, steadier boat may be more comfortable than a day-trip speedboat.
How much is the Similan Islands national park fee?
Mu Ko Similan National Park charges an entry fee, and foreigners pay more than Thai nationals under the standard national park rates (typically around 500 THB for foreign adults and around 100 THB for Thais, with children roughly half). Many day-trip operators include this fee in their price, but some charge it separately, so ask before you book. Rates can change — confirm with your tour operator or the national park department before you go.
What should I pack for snorkeling the Similans?
Bring reef-safe sunscreen (ordinary sunscreen damages coral, and at times the park bans products containing harmful chemicals), a long-sleeve rash guard or swim shirt, a hat and sunglasses, motion-sickness tablets for the speedboat, a waterproof dry bag for your phone, and drinking water. Most tours provide a mask and fins, though you can bring your own if you prefer. Never remove coral, shells, or sand from the park — it's strictly prohibited.