The wonderful Museu Marítimo de Ílhavo is in a modern, award-winning building in the town of Ílhavo, 8km south of Aveiro. It covers the history of Portugal's maritime identity, from cod fishing (with superb fishing vessels from the 19th and 20th centuries) to oil paintings on the bows of the moliceiros (the traditional seaweed-harvesting boats). A highlight is the codfish (bacalhau) aquarium, showcasing the Atlantic cod, which the Portuguese have been fishing (and munching on) for centuries.
Entry costs adult/reduced €8/3.50 if included with the associated Santo André ship museum.