Its watershed drains nearly the entire country of Gabon, with some tributaries reaching into the Republic of the Congo, Cameroon, and Equatorial Guinea.

[8] The source of the Ogooué River was discovered in 1894 by Mary Kingsley, an English explorer who travelled up the banks by steamboat and canoe.

[citation needed] The river rises in the northwest of the Bateke Plateaux near Kengue, Republic of Congo.

Towns along the river include Ayem, Adané, Loanda, Lambaréné, Ndjole, Booué, Kankan, Maulongo, Mboungou-Mbadouma, Ndoro, Lastoursville, Moanda, and Franceville near the Congo border.

The first European explorer to trace the river to its source was Pierre Savorgnan de Brazza, who traveled in the area in the 1870s.