How is the water resistance of a watch measured?

On most watches, especially sport watches, the water resistant is given down to a specific depth (like in the ocean or deep lake) i.e. 300m or 1000ft. The manufacturer is saying that the watch will remain water tight to that depth. How this water resistant is tested varies by manufacturer. read more

Water Resistant 50 Meters / 5 Atmospheres / 5 Bar So you've got a watch with 50 meters of water resistance. Congratulations, you are hereby allowed to swim with it. However, you should minimize exposure to the water and probably still take it off. And by no means whatsoever should you dive with your watch. 50 meters of depth will not do it any favors. read more

The water resistance on a watch is obtained by three important factors: Case Back: This refers to how the case back is attached to the watch. Snap-on case backs are sealed by pressure and are considered the least water resistant. read more