series of cataracts (cataract) on the Iguaçu River, 14 miles (23 km) above its confluence with the Alto (Upper) Paraná River, at the Argentina- Brazil border. The falls resemble an elongated horseshoe that extends for 1.7 miles (2.7 km)—nearly three times wider than Niagara Falls in North America and significantly greater than the width of Victoria Falls in Africa. Numerous rocky and wooded islands on the edge of the escarpment over which the Iguaçu River plunges divide the falls into some 275 separate waterfalls or cataracts, varying between 200 and 269 feet (60 and 82 metres) in height. The name of the falls, like that of the river, is derived from a Guaraní word meaning “great water.”

The falls occur along a wide span where the Iguaçu River, flowing westward and then northward, tumbles over the edge of the Paraná Plateau before continuing its course in a canyon. Above the falls, islands and islets spread the river into numerous flows that feed the cataracts. A major portion of the river tumbles into a narrow, semicircular chasm called the Garganta do Diabo (Spanish: Garganta del Diablo 【“Devil's Throat”】); the effect has been described as that of “an ocean plunging into an abyss.” Excellent views of this section (also called Union Falls) can be obtained from both the Brazilian and Argentine sides. Many of the individual falls are broken midway by protruding ledges; the resultant deflection of the water, as well as the spray that arises, creates an array of rainbows. From the foot of the Garganta do Diabo, a curtain of mist rises some 500 feet (150 metres) into the air.

Among the many islands along the falls, the most notable is Isla Grande San Martín, which is situated downstream from the Garganta do Diabo (on the Argentine side). From this island, a fine view of many of the cataracts may be had. Individual falls to be seen from the forest paths and trails on the Argentine side include those known as Dos Hermanas (“Two Sisters”), Bozzetti, San Martín, Escondido (“Hidden”), and Rivadavia. From the Brazilian shore, an impressive panorama of falls can also be seen; among individual Brazilian falls are those known as Benjamin Constant, Deodoro, and Floriano.

Marie Robinson Wright, “The Falls of Iguazu,” National Geographic, August 1906, pp. 456–60; and Edouard Bailby, “The Iguaƈu Falls: Cascading Wonder of the Subtropical Forest,” UNESCO Courier, 48:40–43 (November 1995).