Museu Marítimo de Ílhavo is the best place near Aveiro to understand the region's cod-fishing history and its close relationship with the Ria de Aveiro. The exhibits cover the boats, the fishermen, and the hard Atlantic work behind a food that became central to Portuguese cooking.
There is also fishing-themed art and a large aquarium, so the museum is not only for maritime-history completists. It makes a good inland counterpoint to Aveiro's canals, salt pans, and lagoon trips.