The National Aquarium Denmark, also known as Den Blå Planet (The Blue Planet in Danish) is the largest aquarium in Northern Europe. The building is designed to make visitors feel like they’re underwater, with enveloping tunnels and large glassed areas. There is an immense variety of marine life organised into themed areas: the Ocean Tank with hammerhead sharks and rays; the Northern Seas area, where you can see local species like octopus and otters; the Tropical section with waterfalls and piranhas; and the Coral Reef full of colourful fish.