Oceanarium

The Oceanarium is an oceanarium dedicated to the ocean. It is located in the Parque das Nações, which was the exhibition grounds for the Expo '98.

The Lisbon Oceanarium has a large collection of marine species — birds, mammals, fish, cnidaria, and other marine organisms totaling about 16,000 individuals of 450 species.

The main exhibit is a 1,000-square-metre (11,000 sq ft), 5,000-cubic-metre (180,000 cu ft) tank with four large 49-square-metre (530 sq ft) acrylic windows on its sides, and smaller focus windows strategically located around it to make sure it is a constant component throughout the exhibit space. It is 7 metres (23 ft) deep, which lets pelagic swimmers to swim above the bottom dwellers, and providing the illusion of the open ocean. The water in the center tank is kept at a temperature that will allow both temperate and tropical fish to live here. About 100 species from around the world are kept in this tank, including sharks, rays, chimaeras, various species of tuna, barracudas, groupers, and moray eels. One of the main attractions is a large Sunfish.

Four tanks around the large central tank house four different habitats with their native flora and fauna: the North Atlantic rocky coast, the Antarctic coastal line, the Temperate Pacific kelp forests, and the Tropical Indian coral reefs. These tanks are separated from the central tank only by large sheets of acrylic to provide the illusion of a single large tank. Throughout the first floor there are an additional 25 thematic aquariums with each of the habitats' own characteristics.

The Lisbon Oceanarium is one of the few aquariums in the world to house a sunfish due to their unique and demanding requirements for care. Other interesting species include two large spider crabs and two sea otters named Eusébio and Amália, named after two Portuguese contemporary cultural references.

Despite its intention of representing the open ocean, the Oceanarium has been criticised by several scientists for grouping together species that would never meet in nature.