Ria de Aveiro, also known as Foz do Vouga, is a lagoon that exists in the region of Aveiro, between Ovar and Mira.

It is a shallow coastal lagoon and extensive zones between tides, extending inland from Portugal, parallel to the Atlantic Ocean, over 45 kilometers in length and with a maximum width of 11 kilometers. Its area covers two districts (Aveiro and Coimbra) and the towns of Aveiro, Estarreja, Ílhavo, Mira, Murtosa, Ovar and Vagos.

The estuary is divided into three channels / zones: the Ovar Canal, the Ílhavo Canal and the Mira Canal.