The west coast and the Gulf both offer considerably different experiences scuba diving in Thailand due to their distinct geographical features and marine life and also depending on when you travel to Thailand might make a difference on where you head when you get here!
Strangely enough the west & east coasts of Thailand have a different season to each other, though none of the guide books have pointed this out. In fact most guide books and google even will tell you the best time to dive in Thailand is October to May, but if you arrive in December in the Gulf you will be arriving at deepest darkest monsoon time. And if you think August is whale shark season and arrive in Khao Lak the only getting wet you’ll be doing is dodging rainstorms and surfing the monsoon waves!
The monsoon season in the Gulf of Thailand is just a few weeks around mid November till late December. Christmas is usually a pretty good indicator monsoon is over. The rest of the year its dive dive dive though your open water ferry crossing during June & July sometimes can get a little bouncy!
While on the west coast the monsoon starts around late April and goes on for around 4 or 5 months till the weather improves about mid October. Koh Tao in the Gulf of Thailand is open to scuba diving 12 months a year which makes it a very unique location, though the visibility isn’t great around monsoon time, there are sheltered areas of the island which are flat and calm and clear of the monsoon waves.
On the west coast particularly around the Andaman Sea, which is known for its world-class dive sites such as the Similan Islands, Richelieu Rock, and Hin Daeng/Hin Muang, these sites offer diverse marine ecosystems, vibrant coral reefs, and encounters with larger marine species like whale sharks and manta rays. In season, the visibility on the west coast tends to be excellent, ranging from 20 to 40 meters (66 to 131 feet), providing clear underwater views and fantastic photo opportunities. The dry season from November to April is generally considered the best time to visit, offering calm seas, warm water temperatures, and optimal diving conditions. However, during the monsoon season from May to October, most isolated dive sites around the west coast may be inaccessible due to rougher seas and reduced visibility so lesser known sheltered sites around Phuket, Koh Lanta, and Phi Phi are utilized more during this time of year.
In the Gulf of Thailand, home to popular diving destinations around Koh Tao, Koh Samui, and Koh Phangan, the Gulf of Thailand experiences different weather patterns compared to the west coast. The dry season from January thru to October is the best time to visit, offering pleasant temperatures, calm seas, and good diving conditions. The monsoon season for about 4-6 weeks usually occurs in November but is done by Christmas does bring occasional rainfall and reduced dive site accessibility and rather large waves most noticeable on the journey over to Koh Tao rather than the dive boats to the dive sites. The visibility in the Gulf of Thailand can vary but is generally lower than the west coast, ranging from 5 to 20 meters (16 to 66 feet). However, during the dry season, the visibility can improve significantly opening up beyond 20 meters around the whole island.The diversity of marine life may not be as rich as the west coast, these sites around Koh Tao especially are ideal for beginner divers or those looking to get certified due to their calm waters and shallow reefs.
The best months of the year to come scuba diving in Thailand is if you are on the west coast, particularly the Andaman Sea, offers more diverse and adventurous diving experiences with better visibility then come between November & April. The Gulf of Thailand, on the other hand, known for its beginner-friendly diving conditions and accessibility is accessible all year but the best time is regarded as the Summer months between January & April which is ideal, but you can dive all the way through the year though November and December ain’t great!
When are you going to go scuba diving in Thailand. If you are coming to the west coast look us up at Big Blue Diving in Khao Lak.
If you’re heading to the Gulf catch us at Big Blue Diving on Koh Tao
