Struggling to open my eyes as water pelts my head and soaks my life jacket, I catch my stepfather laughing hysterically. Fear has turned to exhilaration, and a group of soggy Italian tourists behind us are madly shouting for one more run at the falls -- ''Otro! Otro!"
We are touring Iguazú National Park. Set in a subtropical rain forest where Argentina meets Brazil, it is a lush and enchanting place, enticing visitors from around the world who come here to see the thunderous forces of nature at work.
An Eden-like setting, the falls were formed some 200,000 years ago when a crack in the planet's surface created a small ''stair." The rivulet that became the Iguazú River flowed over the crack, and the rocky terrain splintered and gouged, slowly giving shape to 275 waterfalls.
These falls aren't nearly as high as 3,212-foot Angel Falls in Venezuela nor as commercially hyped as 167-foot Niagara Falls, but they are wider. Taken together, Iguazú Falls span more than 1½ miles in width -- which leaves a lot of walking to do.
Home to more than 2,000 species of ferns, orchids, palms and other plants, the Iguazú Falls basin is the next best thing to touring the Amazon. Here, rainbow-billed toucans flit from branch to branch, endangered jaguars and ocelots find refuge, and monkeys call from high treetops.
A maze of catwalks winds past more than a dozen panoramic stations along the falls on the Argentine side -- and several more viewing perches are visible on the Brazilian bank.
After lathering on sunscreen, we start our trek through the park along the ''green trail." Walking along, I stop to read one of the many signs posted in the park warning of dangerous animals.
Wondering what we would do if we actually saw something, we enter the dense jungle. I jump as the biggest lizard I have ever seen scrambles across the path, seeking a shady rock.
