Barcelona Aquarium (L'Aquàrium)

L'Aquàrium de Barcelona opened in 1995 on the Moll d'Espanya pier in Port Vell, part of the same wave of harbourfront redevelopment that followed the 1992 Olympics and turned Barcelona's old industrial port into a leisure and tourism district. It was built at a scale meant to rival the best aquariums in Europe, and its centrepiece Oceanarium — a single vast tank holding 3.7 million litres of seawater — remains one of the largest of its kind on the continent.

The headline feature is an 80-metre glass tunnel running directly through the Oceanarium tank, letting visitors walk beneath sharks, rays, sunfish and moray eels swimming directly overhead — a format that was still relatively novel when the aquarium opened and remains its most memorable single experience. Beyond the tunnel, 35 separate tanks organise displays by Mediterranean and tropical ecosystems, tracing marine habitats from local Catalan coastal waters through to distant coral reefs.