From Puerto Madryn daytrips run to Punta Tombo. This is a penguin colony where you can walk among thousands of penguins between the months of October and March.
Often combined with a visit to Punta Tombo is a boat trip to spot the small black-and-white Commerson's dolphins. During the months of June through March.
Many tour agents run trips to visit Peninsula Valdes. Here one can see penguins and a great number of sea lions and elephant seals, depending on the season. In January, all three can be seen though no whales, including sea lions giving birth. Puerto Piramides is the only major town of Peninsula Valdes. Many tours will have a stopover here -- there is a nice beach and some bars and restaurants. There are boat tours and kitesurfers, among other things.
Punta Lomaseventeen kilometers southwest of Puerto Madryn is a sea lion reserve. It can be reached by bike. Beware- the road is not paved and your bike may sink into the sand. On the up side, there are deserted rocky beaches very lovely if you take any of the side paths off of this sandy road.
The EcoCentro is a great and modern marine interpretation centre offering interactive information on marine life in the region. Located overlooking the gulf to the south of the city on Julio Verne 784. (http://www.ecocentro.org.ar)