Diving with Whalesharks on Koh Tao

When is the best time to see Whalesharks around Koh Tao

The Best Time To See A Whaleshark Diving Koh Tao

Thailand has lots to offer for the enthusiastic tourist; from the breath-taking scenery, amazing temples, tasty food, and hustle and bustle of Bangkok to the beautiful Islands that line its coasts. On the east coast lies the gulf of Thailand and here is where you’ll find 3 picture perfect paradise Islands.

The smallest and most charming of these three islands is Koh Tao. It has a reputation as a world famous scuba diving destination and specifically the most popular place in the world to learn to dive.


The island, surrounded by dive sites that range from beginner all the way up to technical diving is popular for its marine life and colourful tropical corals. Perhaps what is it most famed for is frequent sightings of its most famous regular visitor and the fish just about everybody wants to see – the Rhincodon typus, more commonly known as the Whaleshark.

Gentle Giants

Whalesharks can grow up to 15 metres long and weigh over 40 tons making it the largest fish that lives in the world. As big as they are, they are very calm creatures, completely harmless to divers.  They feed on only plankton and small fish that are filtered from the ocean by their large mouths that, unlike most shark species is located on the front of the head rather than the underside.


Known to inhabit both deep and shallow coastal waters, lagoons and on close to coral reefs, they can be found in most tropical climates as they cruise around the warm waters of countries such as Australia, Mexico, Philippines, Honduras and Thailand.

Although not too much is known about this immense creature, it is estimated that whale sharks may live to over 100 years of age, reaching maturity at around 30 years. They are thought to have a fast growth rate when very young, which then slows down, taking them a long time to reach maturity and adding to the vulnerability of this iconic species.

Around Koh Tao we generally get the younger whale sharks.  They are gentle and generally very curious and can even be playful with scuba divers, its not unusual to see them swimming through and playing with our bubbles! They also make great subjects for underwater videographers and photographers as they are slow swimmers and will often stay on a dive site for long periods of time.

The Big Question

The question “Where can I see Whalesharks on Koh Tao?” is a very common one. The easiest answer is in the water! Of course there is an element of luck you have to be in the right place at the right time, and although I have snorkelled with Whalesharks most dive sites are not suitable for snorkelling.

The Whaleshark decided to stay around close to the surface for what seemed like forever playing with the spray from around the boat. To be honest however, you need to be diving to be in with a chance.

There have been many lucky student divers that have been able to see these amazing creatures while taking their PADI Open Water course. I once taught a course when we saw Whalesharks on 3 of the 4 open water training dives. It was all so exciting and definitely made for a once in a life time experience.


We have even had customers making their very first dive as part of a discover scuba dive experience, imagine the first time you have ever been underwater blowing bubbles and you see this mighty creature swimming above you.

One word… Amazing! Although this is admittedly rare as normally we see Whalesharks at some of the deeper, outlying dive sites that aren’t suitable for DSDs.

Realistically you would need to be a certified PADI Open Water diver at a minimum to dive the sites Whalesharks are most often seen such as Chumphon Pinnacles or South West and these sites are best enjoyed by Advanced Open Water divers.

Being an advanced diver gives you better flexibility of depth as you can dive to 30m that enables you to fully enjoy the more famous dive sites where these gentle giants frequent. Saying this I’ve seen Whalesharks at dive sites such as White Rock that we often use for open water training dives too!

The can be no guarantee of seeing a whaleshark as when you are diving in the ocean it is such a vast space. When I was learning to dive myself, my very wise instructor told me that diving is like going on safari, not like going to the zoo. Of course though the more you dive the better chance you have of seeing the biggest fish in the sea.

So which dive site exactly?

The most common dive sites we see these graceful beings are at Sail Rock, Southwest Pinnacle and Chumphon Pinnacle, all deep dive sites located a short distance from the island.

These are also Koh Tao’s most popular dive sites in part due to the diversity of marine life – not just Whalesharks – that live in and around these sites.

We visit these sights often and although each time we go, we keep our fingers crossed in the hope we see the biggest and spottiest fish of them all.  


However even without a whaleshark sighting, it is common to dive with large schools of Barracuda and Trevally and spot giant groupers in the shadows close to the granite pinnacles of these sites, which still make the visit well worth while!

There is also a huge array of colourful marine life commonly associated with the tropical waters.

Two other dive sites popular with Whalesharks are Shark Island, located off the south west of Koh Tao and Hin Wong Pinnacle over on the east side of the island. Again both these dive sites are classed as advanced sites and can often be two of Koh Tao’s more challenging dives due to currents.

Occasionally Whalesharks are spotted at White Rock and Twins, two of Koh Tao’s dive sites popular for PADI Open Water Course training dives. Both of these dive sites are located off the west cost of Koh Tao with Twins one of the 4 popular sites located just off Koh Nang Yuan Island.

Even if you don’t see a whale shark on white rock and twins you are very likely to see one of the many sea turtles that have made their home on these dive sites.

When is Whaleshark Season

The million-dollar question – well for scuba divers visiting Koh Tao anyway!

Many dive destinations where Whalesharks visit and migrate to have a specific time of the year that is most common to spot Whalesharks. Not much is known about the specifics of whaleshark migration, except that they can travel thousands of miles a year. Here on Koh Tao though, we are lucky enough to see these amazing creatures all year round.

Although there are specific times of year when visiting Whalesharks are more common to our dive sites, they can turn up out of the deep blue at any time!

Generally speaking there are two periods of the year when spotting these fantastic creatures seems to be more common than the rest of the year.

The first period is March / April / May, this actually coincides with the best time to dive Koh Tao as the weather is usually excellent, nice and hot with stunning sunsets to enjoy at the end of the day.


The beautiful sunny days with little or no wind create excellent diving conditions and we get extra whalesharks who also seem to enjoy these conditions too!

This time of year we have been known to experience something of a whaleshark bonanza with multiple dive trips seeing multiple whalesharks at multiple dive sites – all at the same time!

The second time of the year where Whalesharks are more frequent is October / November / early December.  This last month we have been seeing them almost on a daily basis! Even now as we come out of monsoon season the conditions in the water are still fantastic. With visibility at most sites upwards of 15 meters and lovely warm 30 degree water. There has never been a better time to visit us!

Why this time? Whalesharks have sensory cells in the nasal grooves above the mouth, and these help the whaleshark detect food in the water. It has been suggested that whaleshark movement patterns are linked with coral spawning and plankton blooms.

This could explain why we see a lot of them at this time, as the rainy season soaks Northern Thailand, a lot of nutrients gets washed into the water creating plenty of micro-algae that in turn attracts Whalesharks.

The deep dive sites of Chumphon and Sail Rock see a lot of extra activity especially at this time of year from our favourite big spotty fish. As I write this, sitting at my desk there is a whaleshark right now gracing our lucky divers with its presence at Twin Peaks dive site, very popular for Open Water Training dives!

How to behave around a Whaleshark

It is important to remember that while sharing water with these amazing creatures, it is a once in a lifetime experience and ticks off a bucket list experience for most people. But it is imperative that we understand the do’s and don’ts of our behaviour around them and it is very important to treat these creatures with the utmost respect.


Here on Koh Tao and especially here at Crystal we adhere to Whaleshark standards and guidelines that ensure we do not endanger, harm or harass the fish. This also means divers can enjoy their whaleshark experience to the maximum.

So a few very simple rules to follow, or actually a bit of common sense really.

Do not touch the animal

Do not chase the animal

Stay a minimum of 4m away from the head and 6m away from the tail

Do not use flash photography

No Feeding

There are very few known predators of the whaleshark, although it has been discovered that blue marling and big sharks will sometimes prey on the smaller individuals. The most significant threat to this beautiful species appears to be us. Humans.

Whalesharks large size, slow speed and habit of swimming close to the surface (even though they can reach depths of over 1500 meters), which unfortunately makes them easy to kill. Although their skin can be up to 14cm thick they are still very vulnerable to fishing and boat injuries or being captured, whether accidentally or not in fishing nets. Even floating plastic rubbish, they might swallow can cause injury or sadly, in many cases kills the shark.

Unfortunately, these fish are listed on the vulnerable species due to their small population size. The number of whale sharks has more than halved over the last 75 years, with legal and illegal fishing causing entanglement problems.

Whalesharks still get caught up in lines and nets as well as collide with boats and this is responsible for many premature deaths. Unfortunately, despite being on the endangered list they are still being hunted in certain areas of the world, with their fins being prized ingredients for shark fin soup.

Like human fingerprints, whale sharks have a unique pattern of spots that allow individual sharks to be identified. We have a special page specifically for the Whalesharks spotted around Koh Tao and neighbouring islands, by submitting your photos and videos of our sharks to this page, we can help to track and monitor them, and see how our residents are getting on find this at Facebook Whalesharks Group.

There is also a worldwide site and by taking photos and sharing them with ‘The Wildbook for Whalesharks photo-identification library’ (who’s website is https://www.whaleshark.org/you can help marine biologists to learn more about these amazing creatures.

The library is a visual database of Whaleshark encounters and of individually catalogued Whalesharks. It uses photographs of skin patterns behind the gills and of any scars to distinguish between individual fish.

Author: Nina Horne (PADI MSDT #355693)

Crystal Dive Koh Tao

7/1 Moo 2
Tambon Ko Tao
Koh Tao
Surat Thani

E-mail: info@crystaldive.com

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