It's the largest or all the sharks and also the largest fish in the ocean. Officially they grow up to 12.5 meter in length, with unconfirmed reports of animals up to 18 meters have been reported! Despite their massive size they are filter feeders, mainly feeding on plankton and are not aggressive in any way. Most divers will have this incredible animal on their bucket list, and Thailand is a great place to visit them.
Where to find them
The whale sharks inhabit tropical and warm oceans world wide, and both the Gulf of Thailand and the Andaman sea enjoy regular visits throughout the seasons. Most of the individuals that visit are sub-adults, ranging from 2 - 8 meters in length.
The smaller ones quite often display curious behavior towards divers, snorkelers and boats. They have been known to hang around for hours or days at the same dive sites and often swimming close to divers to check them out. They even seem to enjoy being brushed by the bubbles from scuba divers, and can sometimes be seen repeatedly hanging above a group of divers.
You can encounter whale sharks nearly everywhere in Thailand, but some areas will give you better chances then others. The one area with the most reported sightings in 2017 was Koh Tao and it's surrounding dive sites. Also nearby Mu Koh Chumphon National Marine Park had plenty of observations. Another spot in the Gulf is the legendary Ko Losin to the south.
On the Andaman coast the Similan Islands give the best chance for encounters during their main season. Also the famous Hin Daeng & Hin Muang get sightings yearly.
Despite their massive size and distribution, we know very little about whale sharks. None have ever been observed mating or giving birth, and we have no clear evidence to support where or when such behavior occurs.
What we do know is that the females carry up to 300 eggs or more which are born as live pups. Whale Sharks have an estimated life span up to 70-100 years, and reach sexual maturity at about 30 years of age.
Globally we know very little about their numbers. They are considered endangered by the IUCN and are listed under
Appendix II of CITES.
Locally in Thailand we have citizen research programs looking at identifying individuals and studying their migration patterns and behavior. Scuba divers around the country is asked to take photos of the whale sharks to help identify and provide data to researchers. If you have images of whale sharks from anywhere in Thailand, please submit them on facebook here!
When to see them
Spotting a whale shark takes more then a bit of luck, as you need to be at the right dive site, at the right day at the right time (and not let them swim passed behind you!). But statistically speaking, there are times and places you are more likely to see throughout the year.
On Koh Tao whale sharks are generally spotted all year. But there have always been more of them between late Feb and May. 2017 was an incredible year, with up to 5-10 individuals being spotted each day at various dive sites around the island!
At Similans, they are generally spotted during the entire season, from October/November through to May.