AlanF said:
Pygmy elephants in Northern Borneo. I wouldn't have liked to use shorter than 400mm for this shot.
I quite agree... But I was in a situation in South Africa (Addo Elephant Park) once where we stopped at a good distance of a large family of African Elephants when just 5 meters behind our rental VW Polo suddenly the rest of the family appeared out of the brushes... I was so busy looking for a way out that I didn't even consider taking pictures when this group walked past our tin can - two feet between me and the passing elephant...
Luckily they were friendly and not agitated - not really interested in us - and I made sure I did not arouse them in any way
... and these African ones are BIG (picture taken earlier

)