It is best to avoid driving through water when you do not know how deep it is. However, flash flooding can still surprise victims, so it is good to keep something in your vehicle that can get you out of danger. A Detroit Newsarticle says the power punch can help you break out through a window if you are trapped under water in a vehicle. The power punch smashes the window so that you can swim out to safety. In the article a a retired firefighter/paramedic and underwater rescue diver says:
I would like to suggest a trip to Sears for the purpose of purchasing a
spring-loaded center punch, aka power punch. If you are unfortunate enough
to find yourself trapped in a vehicle underwater, you need only to hold
the point of the punch against the window, and push to load the spring.
Presto -- no more window. This method works equally well on the side and
rear windows of a car, but not as well on the windshield because it's a
different kind of safety glass. The punch can be taped to the inside of a
console, or anyplace else where it will be easy to find in an emergency.
Columnist Ray Magliozzi says that there are also "emergency hammers designed for this purpose, and flashlights that have glass-breaking points on the bottom." The article also recommends another device called the Escape Tip which hooks onto a seat belt.
