We were passing through Hamburg in 2017, visited the zoo. It's very huge. Many animals walk freely on the territory. There are only predatory and dangerous animals in cages and aviaries. It's a pity we didn't have time to see everything!
A huge beautiful zoo. Entertainment for the whole day. I liked it more than in Berlin. There is a cold area with penguins (it's worth grabbing a sweatshirt). There is an aquarium, an exotarium, a polar bear, walruses and much more. Peacocks walk among people :) the choice of food is not very rich, fried potatoes, sausages, ice cream, the price tag is higher (in such places they are usually overpriced). I strongly advise you to visit and allocate more time :)
A very, very cool zoo. Huge. They didn't get around it at one time. After such a zoo, you don't even want to go to other ones. Some animals walk quietly around the zoo, others have a lot of space in their enclosures. I was amazed by the elephants who take a coin and thank me for it. I strongly advise anyone who will be in Hamburg to visit this place.