Wikipedia says that it is perfectly safe to swim in the immediate vicinity of Whale Sharks, Rhincodon typus, the largest extant species of fish which can reach a length of over 40′.
Whale Sharks are docile, only eat plankton, and the worst thing that can happen is the Whale Shark might accidentally bump you with his majestic tail.
Still, the diver in the Daily Mail photo looks concerned about getting sucked into that enormous gaping maw with all the plankton and finding out the hard way what those more than 300 rows of tiny teeth can do.
Who knows? The occasional diver may go nicely as an accent with one’s plankton.
Hat tip to Karen L. Myers.