The Sanaga River is a river of South Province, Cameroon, Centre Province, Cameroon, and West Province, Cameroon. Its length is about 600 kilometers.

The Sanaga River (formerly German:Zannaga) forms a boundary between two tropical moist forest ecoregions. The Cross-Sanaga-Bioko coastal forests lie to the north between the Sanaga River and the Cross River of Nigeria, and the Atlantic Equatorial coastal forests extend south of the river through southwestern Cameroon and Equatorial Guinea, Gabon, Republic of the Congo, Cabinda, and Democratic Republic of the Congo.