The Parana and Uruguay rivers join to form which estuary?

The Paraná and Uruguay rivers join to form the Río de la Plata estuary.

Their confluence occurs at Punta Gorda, between Argentina and Uruguay. From there, the Río de la Plata widens eastward before opening into the South Atlantic Ocean. It is a major outlet for the enormous La Plata Basin, which also includes the Paraguay River and reaches deep into the interior of South America.

The Río de la Plata is often called a river, but geographers classify it as an estuary because freshwater mixes with Atlantic seawater. Its funnel-shaped waters extend for about 290 kilometres and reach a maximum width of roughly 220 kilometres.

Another common misconception is that it is simply the mouth of the Paraná. In fact, both the Paraná and Uruguay contribute to the estuary, which also forms much of the international boundary between Argentina and Uruguay. Buenos Aires and Montevideo sit on opposite shores.