Marakele National Park in South Africa is reputed for its Rhinos. One of the great experience there is that there are no fences around the campsite, and thus the Rhinos come into the campsite at any time (not only the Rhinos, but those are the most impressive).
It is a unique experience, and while scary, if you follow the guidelines, it is not dangerous. Rhinos do not see properly, and do not mind humans… as long as we do not disturb them and/or they don’t feel threatened. So, to keep safe: no noise and no sudden movement. And if, they spotted you when you move, the trick is to stand still… as a tree… and they will just ignore you (or do not see you as a threat).