"Water proof at 200m" doesn’t mean it can be used to dive up to 200m. The Bar is the best indicator whether it can be use to dive or not.
I read that the water proof spec indicated by the company means you can submerge the watch at that depth without moving it, but as you swim (move your arm), the pressure is asserted to the watch, so it’s not true indicator/test of the capability of the watch.