Would you know what to do if your car crashed into the sea and began to sink? For every foot you descend towards Davey Jones’ Locker, 850 pounds of pressure are being exerted on your car door, making the simple act of opening it and exiting an impossibility at the worst possible time.
http://www.autoblog.com/2013/05/21/the-list-0147-escape-a-car-underwater/