The Similan Islands are among Thailand’s most famous dive destinations — clear water, granite boulder formations, and healthy reefs when the park is open.
Park season
The Similan National Park typically opens from mid-October to mid-May. Outside those dates, boats do not operate in the park. Always confirm the current season dates before you book a liveaboard or day trip.
Conditions by month
November to February often brings calmer seas and excellent visibility. March to May can see warmer water and occasional plankton blooms that attract manta rays and whale sharks. Weather still varies year to year, so flexibility helps.
Day trip vs liveaboard
Day trips from Khao Lak reach a selection of sites and return the same evening. Liveaboards spend several nights in the park, diving remote spots like Elephant Head Rock and Richelieu Rock (on Surin itineraries). Choose based on how many days you have and whether you want to maximise bottom time.
Sample trips on this site
This demo workspace includes sample Similan-style day trips and liveaboards so you can explore how BIGBLUE DIVERS presents schedules, packages, and booking flows.
Best Time to Dive the Similan Islands
When the national park is open, what the water is like month by month, and how to plan a liveaboard.
June 5, 2026
