only way to tell the time will be the sun (which is no good if you don’t know how to read it). a good watch must be accurate in doing its basic job: telling time.
when you’re in the great outdoors there is going to be some humidity. you may fall in a pond, get caught in the open by a rain or simply sweat. your watch must be able to resist all that and still work properly.
keep in mind that there are two types of watches: waterproof and water resistant. the first version is designed to resist being submerged in water while the second will only resist in situations where 