Iguazu Falls is the waterfall system on the Argentina–Brazil border associated with World Heritage Sites.
The falls are formed by the Iguazu River, which crosses a dramatic basalt landscape before plunging over a broad, semicircular series of cataracts. The system stretches for roughly 2.7 kilometers and contains anywhere from about 150 to 300 individual falls, depending on the river's flow. Its most famous section is the Devil's Throat, a deep, U-shaped chasm where a large share of the river disappears into spray and mist.
The falls are protected on both sides of the international border. Argentina's Iguazú National Park became a UNESCO World Heritage Site in 1984, while Brazil's Iguaçu National Park received the designation in 1986. Strictly speaking, UNESCO listings apply to the national parks rather than to the waterfall alone, but Iguazu Falls is the standard and fair answer to this question.
The name comes from Guaraní or related Indigenous words meaning “big water.” A common mix-up is Niagara Falls, which lies between the United States and Canada; Iguazu is farther south and is surrounded by subtropical Atlantic Forest.