Salt extraction in the Aveiro region is already an ancient activity, with records of its practice dating back to 959, when the estuary was not yet what it is today and preceding the founding of the Nation itself. It extended from Estarreja to Ílhavo and the occupied area oscillated over the centuries, consistent with the variations in the morphology of the Ría itself, even with great dynamism in that period. Currently, within the space of the Aveiro Salt Flat (a large area of ​​almost 2,600ha), some Salt Marinas (or salt flats) are still active. The marnotos (salt workers) carry out hard, manual work during spring and summer, the favorable times for the salt harvest. The hypnotizing regularity of the small rectangles where the salt water rests in the different phases of the process gives the lagoon landscape a unique and distinctive appearance in the Aveiro Estuary. Simultaneously, some of the spaces once dedicated to salt production have been readapted for other important marine activities, such as the production of salicornia for human consumption, extensive (or semi-intensive) fish farming of sea bass and sea bream, or the production of macroalgae. . The Salt Marinas, stable and rich in nutrients, also function as a favorable habitat for many species of animals (with relevance for aquatic birds) that find food and protection here.