The course is formed at the confluence of the
Paranaiba and
Rio Grande rivers in southern Brazil. From the confluence the river flows in a generally southwestern direction for about before encountering the city of
Saltos del Guaira, Paraguay. This was once the location of the
Guaíra Falls (Sete Quedas waterfalls, where the Paraná fell over a series of seven cascades. This natural feature was said to rival the world-famous
Iguazu Falls to the south. The falls were flooded, however, by the construction of the
Itaipu Dam, which began operating in 1984. For approximately the next , the Paraná flows southward and forms a natural boundary between Paraguay and Brazil until the confluence with the
Iguazu River. Further upstream from this confluence, however, the river is dammed by the Itaipu Dam, the third largest
hydroelectric power plant in the world (following the
Three Gorges Dam and the
Baihetan Dam, both in the
People's Republic of China), creating a massive, shallow reservoir behind it. After merging with the Iguazu, the Paraná becomes the natural border between Paraguay and Argentina. Overlooking the Paraná River from
Encarnación, Paraguay, across the river, is downtown Posadas, Argentina. The river continues its general southward course for about before making a gradual turn to the west for another , and then encounters the
Paraguay River, the largest tributary along the course of the river. Before this confluence, the river passes through a second major hydroelectric project, the
Yacyretá Dam, a joint project between Paraguay and Argentina. The massive reservoir formed by the project has been the source of a number of problems for people living along the river, most notably the poorer merchants and residents in the low-lying areas of Encarnación, a major city on the southern border of Paraguay. River levels rose dramatically upon completion of the dam, flooding out large sections of the city's lower areas. From the confluence with the Paraguay River, the Paraná again turns to the south for another approximately through Argentina, making a slow turn back to the east near the city of
Rosario for the final stretch of less than before merging with the
Uruguay River to form the
Río de la Plata. This flows into the
Atlantic Ocean. During the part of its course downstream from the city of
Diamante, Entre Ríos, it splits into several arms and it forms the
Paraná Delta. ==Tributaries==