- Rí·o [ree-oh; Spanish ree-aw] /ˈri oʊ; Spanish ˈri ɔ/, a river in N Argentina, flowing SE to the Paraná River. About 1200 miles (1930 km) long.
- a river in N Argentina, rising in the Andes as the Juramento and flowing southeast to the Paraná River. Length: 2012 km (1250 miles)
- a river in W Argentina, rising near the Chilean border as the Desaguadero and flowing south to the Colorado River. Length: about 1365 km (850 miles)