We have seen them a few times, but only when we go on foot 
looking for them! A group of 3 walked past our camp once and 
we heard them. We followed and got too close: a male elephant 
turned around and waved his ears at us. After running behind the 
nearest tree we kept our distance.
I am happy they are agressive. It keeps them fairly safe.

There is a walk you can do down the ugab river from rhino camp
 to ugab wilderness camp. The river is usually dry. The trees 
and animals are AMAZING!