Even if there is no zoo in the city of Porto Alegre itself, Parque Zoológico Sapucaia is only about one hour away with the Trensurb and a local mini bus (Lotacao 7).
The area is an impressive territory of local flora (620 hectares of which 160 ha is open to visitors) and walking around the park is a great exercise itself. Also, it is a great activity for the whole family on a weekend as you have the option to bring your own food (or chimarrao) and set up a picnic at one of the many tables in the woods.
Even if the number of animals is not extremely high, you can observe some local and international species of every kind: mammals like bears, panthers, zebras, llamas, camels, deers, various types of monkeys; numerous birds like toucans, swans, ostrich and parrots, crocodiles and other reptiles etc.
The zoo also offers some organised visits and programs for schools as part of an ecological education initiative.
The entrance fee is really cheap (only R$ 9 even for adults) so it is definitely a good deal and you will enjoy being on fresh air and spotting some furry creatures.
Highway to Porto Alegre 