For small items i.e matches, tinder, etc. I so a vacuum sealer guy. You can include a ziplock bag so that after you open the sealed bag you can reseal it somewhat. for larger items like sleeping bags the (waterproof) bags available really won't handle being submerged for an extended period, but what are the odds? They will do well for you providing you give them some shelter from the elements. I went to Ft. Lewis WA. with stuff I thought was waterproof, and learned you can't just leave them out in the weather.