The biggest marine aquarium in South America is located within walking distance of the cruise port (Píer Mauá). Across five floors of AquaRio are more than 5,000 marine animals representing 350 species. They are displayed in 28 precincts representing their natural habitat. The largest is nearly a million-gallon tank called Recinto Oceânico (Oceanic Enclosure). The tunnel lets you feel underwater as the rays, sharks and schools of fish swim around you. There are also plenty of interactive opportunities for children.