Leather Pouches or Bags.

I have several leather pouches made to contain different materials. Drawstring pouches are good for any items that do not have to be kept dry. The closure on a drawstring pouch will not keep water out.
The easiest way to make a waterproof leather bag is to gather, fold and tie the top of the bag, or roll the top of the bag and of course grease it.

This drawstring fire-bag will work fine, so long as water can not get into the top. If submerged in water by a fall in the creek or the boat gets swamped, then the contents will get wet.

This fire-bag when the top is rolled down becomes half the size, and it will keep water out.

This gunpowder bag top has been gathered, folded over and then tied. Whether it contains gunpowder or spare tinder, it is important that no water gets inside. Food bags can be made and secured in the same fashion.