Why do my watches keep getting water in them?

Question

I lifeguard and teach swimming lessons and my watches always get water in them, but they continue to work. The screen generally fogs up and water droplets hug the screen and I then go return it and buy another one. I don't understand why these watches allow water to get into them when they are all water resistant up to at 50 meters. The only things that I feel may encourage water to get in is that I wear the watch so that the time lies on my inner part of my wrist instead of on the upper part.

Answer 1

By a decent watch.  I have a Swiss Military, about $150, i'm in the water all the time, and no problems.