Re water resistance numbers, keep in mind the meters mean the equivalent pressure in atmospheres, it doesn't mean you can actually dive with it to that depth.
Not only that, plenty of watch makers have been caught out by exaggerating ratings.
Helson were embarrassed by this a few times, which is one of the reasons that you can trust their ratings now...they get called out badly if they do pull a fast one.
Re water resistance numbers, keep in mind the meters mean the equivalent pressure in atmospheres, it doesn't mean you can actually dive with it to that depth.