Guaíra Falls were a series of immense waterfalls on the Paraná River along the border between Brazil and Paraguay. The falls no longer exist, inundated in 1982 by the impoundment of the Itaipu Dam reservoir. While published figures vary, ranging from 470,000 cubic feet (13,000 m3) per second to 1,750,000 cubic feet (50,000 m3) per second, Guaíra's flow rate was among the greatest of any falls on earth.
The falls comprised 18 cataracts clustered in seven groups—hence their Portuguese name, Sete Quedas (Seven Falls)—near the Brazilian municipality of Guaíra and Salto de Guairá, the easternmost city in Paraguay. The falls were located at a point where the Paraná River was forced through a narrow gorge. At the head of the falls, the river narrowed sharply from a width of about 1,250 feet (380 m) to 200 feet (61 m). The total height of the falls was approximately 375 feet (114 m), while the largest individual cataract was 130 feet (40 m) high. The roar of the plunging water could be heard from 20 miles (32 km) away.