Due to the mechanics that go into a true blue altimeter watch, they’re not going to be truly waterproof. The difference is, you should be able to submerge a waterproof watch without negatively impacting the performance or function of the watch. Water resistant means you’ll be okay in light rain, or if a splash from a nearby river or waterfall coats your watch. Submersion is another story entirely, and very few brands ever try to make a true altimeter watch that’s completely waterproof.\r