Addo National Park is the best place in South Africa if you want to see elephants. The full name of the park Addo Elephant National Park is for a reason.
Park was founded 80 years ago to safe remaining elephants in the area. Currently there are over 500 elephants in the Addo elephant park and you definitely will see a lot of them by driving around the park. In the park there are almost 50 black rhino, but it is more difficult to spot them .