As part of the ten essentials, carrying an emergency shelter can save your life. There are several types of emergency shelters to protect you from wind and rain in case you get stranded or injured on the trail. Options include an ultralight tarp, a bivy sack, an emergency space blanket (which packs small and weighs just ounces) or even a large plastic trash bag. It’s important to understand that your tent is only your emergency shelter if you have it with you at all times (a tent left behind at your camp is not sufficient).