[2] The São Francisco originates in the Canastra mountain range in the central-western part of the state of Minas Gerais.

He explored the central highlands, canoeing down the São Francisco river from its source to the falls of Paulo Afonso.

The main tributaries are: The São Francisco is naturally navigable all through the year between Pirapora (Minas Gerais) and the twin cities of Petrolina (Pernambuco) and Juazeiro (Bahia), a length of 1,371 kilometres (852 mi).

As of 2009, a single boat, the Benjamim Guimarães, remains in activity, making short-distance tourist cruises from Pirapora to São Romão and back.

[12] More than 40 annual killifish species are found in the São Francisco River basin, especially from the genera Cynolebias and Hypsolebias.

Beginning in Minas Gerais, the river passes by Pirapora, São Francisco, Januária, Bom Jesus da Lapa, the twin cities of Petrolina and Juazeiro, and Paulo Afonso.

The river's hydroelectric potential started being harnessed in 1955, when the Paulo Afonso dam was built between Bahia and Alagoas.

The Sobradinho reservoir is one of the largest artificial lakes in the world, with an area of 4,214 square kilometres (1,627 sq mi).

From Paulo Afonso to the historic town of Penedo (Alagoas), the river lies at the bottom of a gorge or steep sided valley.

Environmentalists argue that the project will do more harm than good, benefitting only large landowners and a very small population, while bringing considerable ecological impact.