The Washington ferries don't routinely check backpacks or coolers. Most I've been on have been full or near capacity.
If you've ever taken your car across the border, you know they question you thoroughly and humorlessly. Foot traffic on the ferries is a whole 'nother ballgame. If inspections were done adequately, that backpack would have been searched before it became a security question. Seems to me the cost of a ferry and numerous people and vehicles would warrant someone doing cursory screening of passengers and vehicles, but nooooooooooooooooooooooooooooo. Guessing it will take the worst case scenario before they get it together and protect passengers, crew and ferries...and its not as if this wasn't mentioned in the past as a possible terrorist target.
I couldn't agree with you more MamaD, and, with some of the ferries going back and forth to Canada every day, it's just a matter of time...