Originally Posted by
earlofsodbury
I'm amazed you of all people are asking that question! Surely you're aware - for all the claims of watertightness to multifathom depths - that there is often a disjunct between that nominal figure and recommended usage according to many manufacturers? So extreme is this, that the manual for a 50m rated watch I briefly owned by "a major Japanese manufacturer" advised me that I should remove it in the shower! They are very likely just covering their arses, but it hardly inspires confidence.
There are other factors beyond immersion - heat, extreme cold, soaps, surfactants, solvents, acids, alkalis, pollutants, chemicals, salt, sweat, &c &c can all make a nonsense of some kinds of sealing and you can multiply that by time and neglect! And what of things like power-washers and dental water-picks for example? Localised pressure can be pretty intense...
Personally: the reason, as should be obvious from that list, is I like tool watches - watches that are tougher than I am, preferably overengineered to Brunellian levels. Overspecified? Gimme! GIMME!!!