• Crossing the Panama Canal  east to west to reach the Pacific Ocean.

Related articles on this site:

• Riddles:  The Riddle of the Sphinx and other classics, old and new.
• Go south, east, north and you're back...  not necessarily to the North Pole!
• Equating a right angle and an obtuse angle,  with a clever false proof.
• Choosing a raise:  Trust common sense, beware of  fallacious accounting.
• Mathematical Games (Two Players): Winning Strategies.
• Mathematical "Magic" Tricks.