The Pretoria Zoo is big, really, really big… 85-hectares with over 3000 specimens of mammals, birds, fishes, invertebrate, reptiles and amphibians – and trying to see all in just a day really takes a toll on your feet. (I would recommend hiring a golf cart for the day.) I have seen animals in there I forgot even existed.
I also took a ride on their cable car track – this is something I would not recommend to the faint of heart. It was the most terrifying experience ever (counting that I stood at the top of the Eiffel and walked down the stairs of the Sagrada Familia church in Barcelona). The cars are very small and the wind just swings it around as if it is nothing!
You can also visit their Aquarium (very nice specimens to be seen here) and Reptile Park that are part of the Zoo facility. They claim their Aquarium is the largest inland marine aquarium in South Africa but I think Ushaka Marine is (don't quote me on that though!).
Tree huggers and eco fanatics will love the Pretoria Zoo as it boasts a large collection of exotic trees.