Not only is this one of the largest aquariums in the world, it also has one of the best designs for such a space. It stands in the middle of the river and contains over 25,000 sea creatures. Most of them are living in a gigantic tank visible from four different levels, and although they may seem to be swimming together, sharks are separated from smaller defenseless fish by invisible acrylic walls.
![Oceanarium](https://onhostportugal.com/wp-content/uploads/2016/04/shutterstock_80172.jpg)