Colored trash bags are hard to find, but should be considered whenever hiking. They are
sold in tear-off rolls. If one is hosting a boy-scout troop or group or children hikers you can use the
roll and provide every child with one of each color. Darker colors for snow areas (blue). Lighter ones (yellow) for forests.
The down-side is that the colored bags are only available in the lightest strength and thickness.
Think about providing each child with two high-visibility colored bags, one red and one yellow,
for example. You can use the bag to line the back-pack to waterproof the goodies inside.
Thicker and stronger black trash bags are more appropriate for emergency survival purposes,
but any bag is better than no bag.