The Oceanarium is located at Parque do Nacoes, a redeveloped area of waterfront on the site of Lisbon's Expo 98. It is one of the biggest aquariums in Europe, and is widely regarded as one of the best in the world. The huge main tank is on two levels with around 100 species from around the planet including ocean sunfish, manta ray, sharks, barracudas, groupers and moray eels.  The upper level of the building features four different marine habitats, including sea otters and penguins.  

The Oceanario is fun and informative for all ages. From central Lisbon, it is easy to get to on the Metro (take the red line to Oriente).