What if a physically unfit submariner gets stuck in an escape device or compartment and causes scores to drown behind him or her.
http://en.wikipedia.org/wiki/Submarine_Escape_Training_Tower
http://www.jstor.org/pss/3860391
http://www.onepetro.org/mslib/servlet/onepetropreview?id=OTC-1434-MS&soc=OTC