By Tom Gillespie @TomGillespie1
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Characterised by their enormous open mouths, the gentle giants are the largest living cartilaginous fish in our oceans but pose no threat to humans.
Texas-based underwater photographer Ken Kiefer captured the images while snorkelling near Isla Mujeres off the coast of Mexico.
The shark enthusiast, who took the photos back in July, said: "Swimming with whale sharks is an almost overwhelming experience.
“Being in the open ocean with a shark that is as long as a school bus is a humbling and amazing event.
"There are times that you will be floating over the void and not able to see anything but the sunrays in the deep blue water, and out of the vague distance a huge shape will take focus gliding towards you.”
Adult male whale sharks are usually between 30ft and 40ft in length, but it is reported that some have been spotted as long as 46ft.
The animals have huge mouths which can grow to nearly 5ft wide and contain up to 350 rows of teeth.
The enormous fish are known as filter feeders, meaning they consume food by swimming towards it with their mouths open.
Despite their incredible size whale sharks live on tiny plankton and fish eggs.
According to Hong Kong-based NGO WildLifeRisk, hundreds of whale sharks are killed each year to be used in shark fin soup in countries such as China.
Ken said: “I believe that anyone able to swim side-by-side with this largest fish in the ocean would have a new appreciation for how incredible they are.
“It would change their perspective on the practice of shark finning.”