I've taken several watches on dives just to see if the ratings are real.
Timex Easy Reader, says 30m, failed on a dive that was no more than 15m.
Seiko SKX-007 OTOH, rated to 200m, I have taken it to about 30m with no ill effect.
I've since learned you can have a watch repair shop test this with a pressure chamber and a finely-calibrated displacement-measuring instrument, no water required.
Timex Easy Reader, says 30m, failed on a dive that was no more than 15m.
Seiko SKX-007 OTOH, rated to 200m, I have taken it to about 30m with no ill effect.
I've since learned you can have a watch repair shop test this with a pressure chamber and a finely-calibrated displacement-measuring instrument, no water required.