The District of Aveiro is a district Portuguese, pertaining to the traditional province of the Coastal Beira, except for the councils more to the north than they belong to the Coastal Duero. It limits the north with the District of Oporto, the east with the District of Viseu, the south with the District of Coimbra and the west with the Atlantic Ocean. Area: 2808 km2 (14º greater Portuguese district). Resident population (2001): 713 578. Seat of the district: Aveiro. The district of Aveiro is located, to a large extent, to less than 100 ms of altitude, occupying a coastal plain that gets to have near 40 km in length, in the South part of the district. The landscape of this plain is dominated by Ri'a de Aveiro and the rivers of the hydrographic river basin of the Vouga River (Cértima, Alfusqueiro, Águeda, Antuão and the own Vouga in the coastal plain, and Agadão, Caima and Mau already in the abutments of the mountain range). For east and the north, the relief becomes rougher, rising also in the district of Aveiro until the heights of the Mountain range of Caramulo and Sierre de Arada, extending also until the mountain range of Montemuro, to the northeast. In its North border, the district contacts briefly with the Duero river and some of its affluents (Arda and Paiva). The coast, call Nova Coast, are sandy, a typical landscape of zone to lagunar, with a cord to dunar of variable thickness that separates calm waters of laughs it of Aveiro of the sea.