According to Guaraní legend, a jealous serpent-god created Iguazú Falls by collapsing the riverbed in front of fleeing lovers Naipi and Caroba; Naipi plunged over the ensuing falls to become a rock at their base, while her lover Caroba became a tree condemned to see, but unable to touch, his beloved.

A less fanciful explanation is that the languid Río Iguazú streams over a basalt plateau that ends where an ancient lava flow finally cooled; before reaching the lava’s end, small islands, large rocks, and unseen reefs split the river into multiple channels that become the individual waterfalls that, in sum, form the celebrated cataratas, some more than 70 meters in height.

At this point, in an area stretching more than two kilometers across the Argentine-Brazilian border, at least 1,500 cubic meters of water per second roar over the edge onto an older sedimentary landscape, but the volume can be far greater in flood. With the water’s unstoppable force, the falls are slowly but inexorably receding toward the east.

About 18 kilometers southeast of the town of Puerto Iguazú, and 1,280 kilometers north of Buenos Aires via RN 12, Parque Nacional Iguazú is a 67,000-hectare unit with a roughly 6,000-hectare Reserva Nacional—whose presence has led to rampant commercial development in the vicinity of the falls.