In his eagerness to show his enthusiasm, he was trying to impress the Captain with his expertise learned in Submariner School.
The Captain cut him off quickly and said, “Listen, ‘sir’, it’s real simple. Add the number of times we dive to the number of times we surface. Divide that number by two. If the result doesn’t come out even, don’t open the hatch.”
Image used under a Collective Commons License from: https://commons.wikimedia.org/wiki/File:US_Navy_040730-N-1234E-002_PCU_Virginia_(SSN_774)_returns_to_the_General_Dynamics_Electric_Boat_shipyard.jpg