The Rio de La Plata
La Plata, Río de, a body of water forming the major indentation on the Atlantic coast of South America. It is the estuary of the Paraná and Uruguay rivers, lying between Argentina and Uruguay. The RÍo de la Plata is about 170 miles (270 km) long. It is 25 miles (40 km) wide at Buenos Aires, 60 miles (96 km) wide at Montevideo, and 140 miles (225 km) wide where it flows into the Atlantic. The main ports are Montevideo on the northern shore and Buenos Aires and La Plata on the southern. The estuary is not deep and requires constant dredging. The RÍo de la Plata was discovered by Juan Díaz de Solís, a Spaniard, in 1516.