People instinctively compare Iguaçu to Niagara Falls and Victoria Falls, and Iguaçu wins most of those comparisons. It is taller than Niagara and nearly as wide as Niagara and Victoria combined. Its peak recorded flow rate exceeds both. Eleanor Roosevelt is said to have exclaimed 'Poor Niagara!' upon seeing Iguaçu for the first time, and the quote has stuck because it captures something genuine -- the feeling that you have been measuring waterfalls against the wrong standard your entire life. The centerpiece is the Devil's Throat, a horseshoe-shaped chasm 82 meters high and 150 meters wide that swallows roughly half the river's volume into a permanent cloud of spray. On sunny days, that spray throws double and triple rainbows across the gorge.

Argentina holds the majority of the falls within its Iguazú National Park, declared in 1934. The Brazilian Iguaçu National Park followed in 1939. Both received UNESCO World Heritage status in the 1980s and were later named among the New Seven Wonders of Nature. The experiences they offer are complementary rather than competitive. On the Argentine side, an elaborate network of trails and a small railway bring you to the upper rim, where boardwalks extend directly over the cascades. The Devil's Throat walkway puts you at the precipice itself -- looking straight down into the abyss, drenched by spray, deafened by the roar. The Brazilian side trades proximity for perspective. A single trail, roughly two kilometers long, traces the lower gorge and culminates at a platform that juts into the mist at the base of the largest falls. From here you see the entire horseshoe laid out before you, the scale almost impossible to process.

The parks protect a significant remnant of the Atlantic Forest, a subtropical rainforest ecosystem now reduced to a fraction of its original extent. Within the park boundaries, the forest is lush and largely intact, draped over the basalt cliffs and fed by the constant mist. Five species of toucan live here, including the toco toucan with its oversized orange bill. Great dusky swifts nest behind the curtain of falling water itself, threading through the spray at improbable speeds. Coatis -- raccoon-like mammals with long ringed tails -- have learned that tourist walkways mean food, and they patrol the paths with brazen familiarity. Jaguars, ocelots, giant anteaters, and tapirs inhabit the deeper forest, though sightings are rare enough that trail closures for puma activity still make news among park visitors. Approximately 450 bird species have been recorded, making the parks one of South America's premier birding destinations.

Iguaçu Falls sits at the Triple Frontier -- the point where Argentina, Brazil, and Paraguay converge at the junction of the Iguazu and Paraná rivers. This geographic oddity means three different cities serve as gateways: Puerto Iguazú on the Argentine side, small and charming; Foz do Iguaçu on the Brazilian side, larger and more urban; and Ciudad del Este across the Friendship Bridge in Paraguay, frenetic and duty-free. Border crossings are casual by South American standards, authorities assuming most travelers are day-tripping to see the falls from the other side. The nearby Itaipú Dam -- the second largest in the world -- adds another superlative to a region that collects them. And just a few hours southwest, the ruins of Jesuit missions in Misiones Province offer a very different kind of wonder: carved red sandstone walls where the Guaraní people left their mark in stone, long before anyone thought to build observation platforms over waterfalls.