Although whale sharks are the world’s largest fish, aerial reconnaissance is still the best way to spot them. There is never any guarantee you’ll see one. Whale sharks are shrouded in mystery. No one knows how many there are or what triggers their trans-oceanic migrations. These enigmatic creatures can dive to depths of 700m, yet feed on surface plankton. They can reach 18m in length, but how long they live is unknown. The IUCN lists the whale shark as ‘vulnerable to extinction’. Apart from orcas, humans are their greatest threat. Shark fin soup commands a high price – but so too should the privilege of swimming with these gentle giants. Ecotourism could provide an economically viable alternative to hunting, as long as it is properly managed to minimize disturbance.