If you're stranded in the wilderness, your top priority probably isn't making a To-Do list. But you'll need one. First, Find Water Though people can survive for three days without water, our climate can quickly dehydrate you. Since some local lakes are infected with giardia (a diarrhea-causing bacteria), treat water with iodine tablets, a filtering pump, or a UV pen. Boiling water for 10 minutes will also kill any bacteria. If you don't have any way to purify water, drink only the clearest, fastest-running water around, since it's the cleanest. Don't eat snow--it lowers your body temperature and dehydrates you more. Instead, pack snow into your water bottle and put it inside your jacket; your body heat will melt it down. Finally, Find Food If you're lost, shelter, fire, and water are far more important than food. Humans can survive for up to three weeks without food, so focus instead on getting rescued. Gather more lean-to materials or firewood. If you packed a candy bar, dig in.