If you've kids in tow, bring them here. Much more than just an aquarium, this enormous 'aquatic world' is divided into three pavilions containing polar, tropical and temperate ecosystems. Highlights are the shark tanks, mangrove and rainforest sections, colourful tropical reefs, seals and the penguin display. The numerous films and interactive displays are educational for children and adults alike. It's about 3km east of the city centre.
Buying tickets at the tourist office (for a discount) or online allows you to skip queues (long in summer). Many displays have an English translation; a €1 multilingual audioguide is also available.