Depending upon impact forces, passengers and crew might be stunned, or even unconscious (You know, like some people in Washington?) Those passengers were likely not donned in life vests. People also panic, and they’ll jam exits, open doors to escape fire or, in this case, cabin flooding, which worsens that hazard. Many airline passengers don’t absorb pertinent information from briefings repeated by the cabin crew, and they’ll have no idea what to do when their plane crashes. There are a few previous examples of planes ditching in relatively shallow water which resulted in fatalities. National Airlines flight 193 was such a tragedy.