The worst case scenario is that you get hurt. Actually, the worst case scenario is that you get hurt and don't have a first aid kit with you because you thought it was too heavy to pack. No, wait maybe the worst case scenario is really that you get hurt, and you have your fist aid kit, but it is soaking wet and totally unusable because it wasn't in a waterproof container. The Adventure Medical Ultralight Watertight . 9 First Aid is lightweight, packable, and uses a DryFlex liner to keep water out.