My understanding is that you can't really take a diver's watch listed at 200M down to 200M below the water's surface. If you do, you'd better not move, as the pressure of the water + movement will likely be to much.
That said, I'm never going close to 200M, or even 100M or 50M below the water's surface. I have a watch, in this case the Hamilton Khaki Field Auto, that's listed as 5 ATM. Usually, that correlates to 50M. But I've also heard that running water from a strong faucet landing directly on the watch's crown or caseback can exceed 5 ATM. Any truth to this?
I know there's an chart from Omega listing the different activities for WR listings and activities; does this accurately correlate to all watches?