We spent four days swimming with magnificent whale sharks, the biggest shark species in the world. During our time in Isla Mujeres, Mexico with WildAid, we learned how sharks, mantas, rhinos, elephants, and tigers are being exterminated--those who kill them, those who sell them, and those who consume or display them. WildAid's approach is this: "When the buying stops, the killing can too." And thus, when restaurant consumers in China became aware of what that flavorless bit of cartilage in their soup came from, many stopped ordering shark fin soup and consumption fell about 70%. In Isla Mujeres, sharks were once hunted and their fins displayed in restaurant windows. Now they are strictly protected. The fishermen who once caught sharks now take tourists out to see them. Sharks here and in other places in the world are worth millions in eco-tourism revenue.