Parque Nacional Iguazu is a subtropical rainforest that's split between Argentina and Brazil, though you'll want to make sure you're on the Argentinian side for the grandest of all waterfalls - Garganta del Diablo (Throat of the Devil). This one dwarfs them all in density and power and is an awesome sight to see, especially when there are butterflies fluttering all around like party confetti and landing on every surface, including your hands. Iguazu Falls comprises of over 250 individual waterfalls stretching across 2 miles and is absolutely teeming with wildlife. The moment that really stuck in my head though was turning a bend to a clearing in the park and being completely dumbfounded by the sheer beauty of this rainforest. I couldn't imagine there was a place more gorgeous in the world.