Remember the rule of three or redundancy. Always have a backup for your backup.
A pair and spare, that's what we called it in the Navy!
Somebody has to speak for these people. Y'all got on this boat for different reasons, but y'all come to the same place. So now I'm asking more of you than I have before. Maybe all. Sure as I know anything, I know thisthey will try again. Maybe on another world, maybe on this very ground swept clean. A year from now, ten? They'll swing back to the belief that they can make people...better. And I do not hold to that. So no more runnin'. I aim to misbehave. Mal Reynolds Serenity/Firefly
All great suggestions... but the one's I haven't seen listed so far that I have in my B.O.B.-
Silk head scarf or Shemagh
Canteen w/ metal cup
Water filter straw
Nuts (cashews, sunflower seeds)
...and if you need them, extra pair of glasses. Keep any perscription meds handy too.
Bulgar wheat (a staple for packing. It is par boiled then dried back, so it is precooked and needs only to be rehydrated and heated by adding to boiling water or broth and then left to sit off the heat for ten or fifteen minutes)
Small packs of dried fruit
Small packs of dried vegetables
Small cook set
Lense wipes (the alcohol wipes double as fire starter)