It often seems we get this question on a daily basis. I'm guessing the following information will surprise you.

There's no such thing as a waterproof watch. When subjected to enough pressure for enough time, every watch will eventually fail. Some watches, however, will take longer to break than others. Those watches are water-resistant, and their water-resistance (in terms of atmospheres or meters) is a measure of how much pressure it takes to damage the watch.