Stimulated by the calculation showing that a ping-pong ball does not popcalculation showing that a ping-pong ball does not pop in vacuum, I'm driven to ask how deep in the ocean a ping-pong ball can be brought before it collapses due to pressure.
This has a practical application in that boats have been refloated by the expedient of pumping ping pong balls into their hull.
Youtube ping pong ball boat refloating: http://www.youtube.com/watch?v=4MOJN07XRYw