The Plate Basin is the fourth largest river system in the world. Yet its estuary (the Plate river) is so shallow that a deepened ship channel has to be maintained up to Buenos Aires. Above, the Uruguay is navigable up to Salto, and the Paraná to the hydroelectric dam of Itaipu. At Corrientes, the Paraguay river branches off and is navigable to Carceres in Brazil. Beyond Itaipu, the Tietê-Paraná waterway reaches São Simão, on the Parana's tributary Paranaiba, and Conchas, on the Tiete, thanks to several locks and the Pereira Barreto canal. Itaipu dam (120 m high) is the last obstacle to navigation on the Plate Basin, and a flight of four locks is planned. These were originally planned to be built at the same time as the hydropower scheme, but to date it has not been possible to finance these works.
In Brazil, the other main waterways from south to north are:
- The São Francisco, which is navigable over 1371 km between Pirapora and Juazeiro. Some 40 km above Juazeiro stands the Sobradinho lock (120 m x 17 m, with a 33,5 m rise).
- The Tocantins-Araguaia, where a system of two locks and an intermediary canal is being built at Tucurui, 250 km upstream the river mouth.
- The Amazon, the greatest of south American rivers. From the tributary Rio Negro, the Casiquiare natural canal runs for over 320 km to the Orinoco.
The Orinoco, which lies entirely within Venezuela, is navigable to the Atures rapids some 1126 km from the sea. Its main navigable tributary is the Caroni, and works planned to be completed in 2007 will enable navigation on the Orinoco-Apure axis.