Submarines

The new Ensign was assigned to subs, where he'd dreamed of working
since a young boy. He was trying to impress the Master Chief with his
expertise learned in Sub School.

The Master Chief 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."

Seven Irish sailors drowned trying to push start their submarine, another seven drowned trying to bury them at sea!!!