Bicicleta de Utilização Gratuita de Aveiro - that can be “rented”, for free, in specific spots in the city. You just need to present your Identification Card. See the location here!
To move to near by cities or to the beach, you can try the Bus! All the schedules are available online. To go to the beach, you can catch the bus in Galitos Bus stop during this schedule.
Reaching other Portuguese cities is easy and quite affordable by train. The trains to the main Portuguese cities run regularly, usually at least one per hour, sometimes more. You can find the schedule and prices online.
Let's not forget the TAXI service, a transport available almost everywhere, including Aveiro. You can call to the (+351) 234 385 799 or visit the webpage taxisaveiro.pt.