The choice is about the sea, not the schedule
Every operator's brochure sells the same set of islands, and the meaningful difference between the products is the hull you are sitting in. A speedboat covers more distance and stops at more places; a ferry takes longer and moves through swell rather than over it.
That distinction matters most on the days it matters most. In flat calm, a speedboat is the obvious choice. During the southwest monsoon, when the Andaman is running a swell, the same boat is a punishing few hours and the ferry is the civilised option.
Park fees and the paperwork
The islands most people visit sit inside national parks, and the Department of National Parks charges an entrance fee for foreign visitors on arrival. The park asks you to keep the receipt for inspection after paying, which tells you it is checked.
Ask your operator directly whether the fee is included in the price you were quoted. Some include it and say so; others quote a low headline price and collect the fee at the pier or on the island, which is where a group discovers an unexpected cash requirement.
Seasonal closures
Not every island is open all year. Mu Ko Similan and Mu Ko Surin national parks announced a closure running from 15 May to 15 October 2026, covering both visits and overnight stays, for monsoon safety and ecosystem recovery. That is a recurring annual arrangement rather than a one-time event.
If your trip falls in those months and the Similans were the reason you came, plan around it before booking rather than after. Other destinations remain available, and an operator selling you a Similan trip during a closure period is a reason to walk away.
| Choose | If | Note |
|---|---|---|
| Speedboat | Calm sea, more stops, no back problems | The roughest ride available |
| Ferry | Swell, seasickness, an easier day | Fewer islands in the same time |
| Private longtail | A single nearby beach, your own pace | Weather-dependent and less regulated |
Checking the sea before you commit
The Thai Meteorological Department publishes an English marine and shipping forecast for the Andaman Sea, including wave heights and monsoon conditions. Look at it the night before, and if it is describing significant waves and warning vessels to proceed with caution, that is information about your day trip regardless of what the tour desk says.
Trips do get cancelled in bad weather, and a cancellation is the operator behaving correctly. Book island days early in your stay so a cancelled trip can be moved rather than lost.
What to bring
Reef-safe sunscreen, a hat, more water than the boat provides, a dry bag for anything electronic, and motion sickness medication taken before you board rather than when you start to feel it. Wear something you can swim in under your clothes; changing facilities on these trips range from basic to nonexistent.