Several of the Sea Lions at the St Louis Zoo Sea Lion Sound will follow a hat that is placed against the glass observation tunnel. This one was playing with me, going back and forth, up and down, and going in circles! I would stop and place my hat on the ledge and the Sea Lion would look at it and give me a 'look' that said "ok, get going...move it...move it".

It was a cold winter day and I was the only visitor in the tunnel. Timing is everything!

Nikon D800 w/Nikkor 24-85mm f/2.8-4D
@40mm, f/11, 1/50s, ISO 800