The Lisbon Oceanarium is an oceanarium in Lisbon, Portugal. It is located in the Parque das Nações, which was the exhibition grounds for the Expo '98. It is the largest indoor aquarium in Europe.
The Lisbon Oceanarium has a large collection of marine species — penguins, seagulls and other birds; sea otters (mammals); sharks, rays, chimaeras, seahorses and other bony fish; crustaceans; starfish, sea urchins and other echinoderms; sea anemones, corals and other cnidaria; octopuses, cuttlefish, sea snails and other mollusks; amphibians; jellyfish; marine plants and terrestrial plants and other marine organisms totaling about 16,000 individuals of 450 species.
The main exhibit is a 1,000 m2 (11,000 sq ft), 5,000 m3 (180,000 cu ft) tank with four large 49 m2 (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 m (23 ft) deep, which allows pelagic swimmers to swim above the bottom dwellers, and provides the illusion of the open ocean. About 100 species from around the world are kept in this tank, including sharks, rays, barracudas, groupers, and moray eels. One of the main attractions is a large sunfish.