You might want to get a better bag if you're worried about submersion. Ziplocs are not necessarily completely water tight out of the box, and they degrade pretty quickly in use (like the constant rubbing that'll be produced by carrying it in your pocket all the time). Wad up some toilet paper in an old ziploc or two and submerge them for a few minutes, then check the paper...you might not like the results. Consider a dry bag like rafters/kayakers use.