According to the “Lonely Planet” travel guide, in order to get to Reserva Natural das Dunas de Sao Jacinto, you need to take a bus to Forte de Barra. As it turned out, it is much better to go by bus which takes you to the ferry port, then board a ferry (a combined return ticket for both ferry and bus costs 7 Euro) and then take a 30-minute walk. That's how you will get to the entrance of the reserve.
Sao Jacinto Dunes Natural Reserve is located on a cape which separates Aveiro from the ocean. This means over 700 hectares of wonderful nature: rare specimens of plants and animals, mainly birds.
Pebble beach, sand dunes, sea waves and wind, all these factors led to the creation of several separate areas that can be observed in the reserve. They are so diverse that in some places I walked through a forest (planted to counteract erosion), in others through sand dunes. In the reserve, there are also ponds, which were built to protect Aveiro's nature from extinction. Thanks to that, birds such as herons could establish a colony. The biggest pond, called Pateira, is a winter shelter for many species of water birds.
Admission to the reserve is free. However, you have to “register” at the reception desk before entering the place and upon leaving it. Aveiro reserve is without doubt a real gem you just can't overlook when you are in Portugal. Nonetheless I would not recommend visiting this place during summer season, because the birds hide from the blazing sun and all you can do is take a walk in the forest.