Swimming with whale sharks is something that most tourists to the Maldives look forward to and the turquoise waters that surround the archipelago certainly won't leave you disappointed. At 18 metres in length, whale sharks are the largest known extant fish species and the largest living non-mammalian vertebrate. With their huge size and wide, terminal mouth, these slow-moving, filter-feeding carpet sharks may appear intimidating at first, but they are the last creatures to cause you any harm underwater. However, it is advisable to maintain your distance if you were lucky enough to spot one.