Batman Arkham City Easter Egg - Shark Repellent

This one only appears during initial playthrough. If you come back later on it won't work.

When inside the museum attempting to rescue cops held hostage by the Penguin, you'll come to a flooded room where Batman has to pull himself along on a raft. If you move too quickly on the raft a shark will appear and try to eat you.

Allow the shark to drag you underwater and a death animation will follow, the hint accompanying hint shown will be: "Try using Batman's shark repellent: beating it." The phrase 'shark repellent' is a reference to the 1966 Batman film based on the TV show, where Batman escapes a shark attack using shark repellent.