Add Yahoo as a preferred source to see more of our stories on Google. Tourists visit the Iguazu Falls in Iguazu National Park in Foz do Iguazu, Brazil, last week. Photo by Juan Pablo Pino/EPA Dec. 29 ...

As we rapidly approach the Iguazu Falls, I shout to my step-dad that we're getting too close. Too late. The motorboat with its load of tourists is hurtling straight toward the towering curtain of mist ...