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  • Deep Andaman Team

When to Dive the Similan Islands

Updated: Jan 25, 2020

Liveaboard operators run chartered dive trips to the Similan and Surin islands from the end of October through to mid-May each season, with pick up locations in both Khao Lak and Phuket. Liveaboard trips are undoubtedly the best way to explore the best dive sites in the Andaman Sea, as many of the stand-out locations and best Similan Islands marine life – and especially opportunities to dive with whale sharks and see manta rays - are too remote to be enjoyed on a day trip.

Like most holiday destinations in Thailand, The Similan Islands have two general seasons, dry season and wet season. On the west coast of Thailand monsoon season typically runs from June to September, and during this time the Similan and Surin national marine parks are closed. So Similan Island liveaboard trips are only available throughout the dry season. Do be aware that Thailand weather patterns tend to be very regionalized, therefore it’s always recommended to check the weather and monsoon seasons for all locations you plan to visit on your Thailand diving holiday. For example in the Gulf of Thailand off the east coast, monsoon season typically runs from around the end of October and can last into the New Year. So even though there is little more than 150-200 kilometers separating both of these amazing Thailand diving locations, the conditions can vary significantly between them.

During any monsoon/wet season you can expect heavy rain and strong winds, which are understandably not the best conditions for either long boat trips or favorable scuba diving conditions! To experience the best Asian Liveaboard diving experience, you want calm seas and hot sunny days and perhaps just a light breeze. For the majority of our dry season, this is exactly the type of weather in the Similans that guests can expect, in order to experience the best Thailand Liveaboard aboard the Deep Andaman Queen. The Similan Islands are located just 8 degrees north of the equator, and therefore have a tropical climate, which means some rainstorms can pass through at any time. However throughout the dry season, these are infrequent, and generally only last for an hour or so. Also, it is worth noting that out at sea we experience more sunny days than back on dry land in Phuket or Khao Lak. Liveaboard boats around the Similans and Surin Islands are so far removed from mountainous areas, that the chances of rain are much reduced. So guests aboard our Andaman Liveaboard scuba trips will most likely have to jump in for their next fun dive to get wet, rather than waiting for rainfall!

All this being said, the most reliable months during the Similan Islands dive season tend to be December to April, where the sea is flat and the sky blue and cloudless. These months are also considered to be manta ray season in the Similans, and statistically, the best opportunities for whale shark diving in the Similans is from January to April. Currents have a tendency to become stronger towards the end of February, which is one of the reasons why bigger pelagics are more likely to be drawn to the area around this time. It is worth noting, however, that historically both whale sharks and manta rays have been spotted on our North Andaman Liveaboard trips throughout our operating season, so don’t rule out departure dates in either shoulder season to tick shark diving and diving with manta rays off your Thailand diving bucket list, especially as you can get some great deals on all of our Similan Island liveaboard trips and Myanmar liveaboard trips closer to the beginning and end of each season!

Top dive sites for sightings of the ‘big stuff’ include Richelieu Rock, Boulder City, Koh Bon, and Black Rock. Throughout the liveaboard season, you can expect excellent visibility (typically 20-40meters) and water temperatures at the surface ranging from 26-29°C, with the warmest conditions normally towards the end of the season. Below the surface, there is rarely a drop of much more than 1°C, and light penetration even at depth remains consistently good, which is great news for budding underwater photographers looking to snap some amazing photo memories of their Thailand liveaboard trip.

We hope this has given you some helpful information on when to dive the Similan islands so you can plan your holiday dates and Andaman scuba diving liveaboard trip with us! You can check on our website home page for the most up to date Liveaboard diving deals. You can also check trip availability and book online to secure your place.

If you require any further information, please contact one of our helpful team members on, and we’ll be happy to answer any questions you have and assist you with your booking.

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