Discovery ran a Mythbusters marathon over the holidays. Rewatching the underwater car episode, I noted some things:

Adam could open the door if he did it VERY soon after hitting the water. When he waited and attempted to open the door after it was partially under water, he ran out of air before pressure equalized to where he could open the door (and had to get the regulator Jaime was holding for him in the car).

In a later test, he waited and ventilated while the cabin filled, and was easily able to hold his breath long enough after the water rose past his head for the pressure to equalize and allow him to open the door.

An electric window operated under water for more than 45 minutes. But when they piled enough weight on the window to simulate the pressure of water outside an air-filled car, it jammed and wouldn't move.

Manual window crank failed completely under the same load.

Putting a door in a water tank, and reaching in with just his hand and forearm in the water, Adam was not able to strike the window hard enough to break it with a cell phone or with keys. Even after climbing in the tank, he was not able to kick it hard enough to break it even with a steel-toed shoe. This struck me as the most important thing in the whole show. Even partial submergence in water impeded his motion significantly.

A Life Hammer broke the window on the first strike, under the same "hand and forearm only in the water" condition, as did a center punch (identical function to a Res-Q-Me).


If you go in the water, you better have a specialized tool for breaking that window. If the water inside gets high enough while you unbelt yourself and possibly others in the car, you may not be able to break it with an improvised tool.

Now, if you'll excuse me, I'm going to go practice finding the awl on my Leatherman with my eyes closed. Just in case I can't get my Res-Q-Me OR my Life Hammer.