Okay, I did some reading, and it turns out 100m water resistance is not good enough for diving because of additional pressures from moving your arms and stuff. For diving, you need at least 200m resistance and a screw down crown. Since this watch has neither, it's only okay to get it wet from showering, rain, etc. Swimming with it is risky without the screw down crown, but is arguably okay depending on who you ask.
zerokoolYou should never shower with a watch on. A friend of mine who repairs/collects watches says that's because steam gets where water can't, and degrades the o-rings.