The falls are all about superlatives: On the border between Argentina and Brazil, the thunderous cascades of Iguazz are one of South America's most popular, greatest, and most worthwhile sights. As more than 5,000 cubic yards of water per second roar over the evocatively named Garganta del Diablo (Devil's Throat) and other massive waterfalls, swallows flit through the mist beneath the overhang where ferns and mosses cling to their sheer volcanic walls. The park is more than the falls, though—there are thousands of acres of well-preserved subtropical moist forest, crisscrossed by foot trails, plenty of colorful bird life, and even large mammals ranging from the gregarious coatimundi to the shy but predatory jaguar.