The Aquazoo in Dusseldorf, Germany combines the best of all worlds for people who are into animals. They take the best of a zoo, and aquarium and a history museum to make a very enjoyable experience for people of any age.
It's a great learning experience, and something that is fun to visit multiple times without it getting repetitive in any way whatsoever.
Perhaps the biggest draws are the sperm whale skeleton, and the large shark aquarium that house is the magnificent fish. It doesn't matter if it is children or adults, as everyone enjoys checking out what is offered.