I think its safe to say that this cat has made a friend for life in this really cool video uploaded by n24our on March 6, 2011:

That cat looks a lot like my little buddy (Buster).  However, I suspect Buster would run like hell if some giant, fish-like critter approached him.  And yes, I know that dolphins are mammals.  Its just the whole swimming/fin thing.  Buster wouldn't know the difference.  The only type of aquatic creature he's ever been exposed to comes out of a can.

You can find more cool animal videos here!