To the north of the Ártabro Gulf is a series of small estuaries which, due to their latitudinal position, are considered "Altas" (high). The most western of these, Cedeira, Ortigueira, O Barqueiro and Viveiro, are wider and present sections of abrupt cliff coasts, although inland splendid sandbanks open up such as Vilarrube en Cedeira, Morouzos en Ortigueira and Covas en Viveiro. The eastern estuaries, Foz and Ribadeo, are smaller and the profile of the coast is gentler.
The inhabitants of these estuaries have been secularly isolated from Santiago, the historical centre of Galicia, and from the land routes of the interior of the peninsula. They therefore opened to the sea, their natural outlet, and were always fishing ports, particularly for whales and bonito, and fundamental centres for linen and hemp trading with the Baltic lands. This explains the appearance of customs in Viveiro in the 16th century and also in Ribadeo, and the existence of a pilots' school in Ribadeo in the 19th century.
