The Lisbon Oceanarium is one of Lisbon's most iconic attractions and one of the largest indoor aquariums in Europe. Located in the modern Parque das Nações district, it was originally built for Expo '98 and is designed to represent a journey through the world's oceans.

The aquarium is structured around a vast central tank containing thousands of marine species, including sharks, rays, tuna and other deep-sea fish, creating the illusion of a single global ocean. Surrounding it are four large habitats representing the Atlantic, Pacific, Indian and Antarctic Oceans, allowing visitors to explore different marine ecosystems in one continuous experience.

Beyond the main exhibition, the Oceanário also features sea otters, penguins, jellyfish and immersive temporary exhibitions, all designed to highlight ocean conservation and biodiversity. Its architecture is also notable, appearing to "float" on the water within a large artificial lagoon.

Today, it is widely regarded as one of Lisbon's must-visit cultural attractions, combining education, environmental awareness and a highly immersive visitor experience.