Everyone has seen the photo, so the trick at Iguazú is not finding the falls but choosing the order. The river that rises near Curitiba runs along the Argentina-Brazil border and then drops over a basalt ledge in roughly 275 separate falls, spread over nearly 3 km. About 80 percent of the jumps are on the Argentine side, so build the trip around it. The first European to record them was Álvar Núñez Cabeza de Vaca, in 1541.
Three days is the right length because the park rewards two visits. The second-day ticket is half price, the boat and the rainforest trail need a morning each, and the Brazilian side is a different view that fills a day with the border. A flood can close a circuit with a day's notice, so you want a spare day, not a rushed one.
The plan is based in Puerto Iguazú, the small town on the Argentine side. Day one is the park and the boat, day two the rainforest trail, the town and, on the right nights, the full-moon walk, and day three the Brazilian panorama and the Parque das Aves. Start on a Monday if you can, since both parks are busiest at weekends and on holidays. Honest warning for this year: the Argentine Devil's Throat walkway has been shut since August 2026, and day one says how to handle that. For a longer Brazilian stay, see 3 Days in Foz do Iguaçu, and for the rest of the country start with Argentina.