In Whipsnade Wild Animal Park they've got free roaming Maras. I was quietly sitting on the grass, trying to get a good picture of a resting one, when it suddenly stand up and went away looking in my direction. But I hadn't done anything to disturb it.
I turned around and saw three elephants passing me very closely. Two keepers were taking them on a walk. They got a little drink at the tap and grazed afterwards on the same grass I was sitting on. A bit later one elephant moved to the tap again and opened it to get some more water.
(Of course I was surprised being so close to such big animals, but I stayed calm and handled the whole situation like a professional photographer.)