Rí⋅o de la /ˈriɔ ðɛ lɑ/Show Spelled Pronunciation[ree-aw the lah]Show IPA, an estuary on the SE coast of South America between Argentina and Uruguay, formed by the Uruguay and Paraná rivers, ab. 185 mi. (290 km) long.
Pla·ta (plä'tə, -tä) A wide estuary of southeast South America between Argentina and Uruguay formed by the Paraná and Uruguay rivers and opening on the Atlantic Ocean. It was explored by Magellan in 1520 and Sebastian Cabot from 1526 to 1529.