A bear bag is a device used when camping in areas that bears frequent to keep food and perishable items out of reach of the bear by raising it into the air by some means. The idea is if the bears cannot reach the food, they will not be tempted to venture too close to the camp and thus will not be a danger to humans or themselves. An alternative is to use a bear-resistant food storage container.
Lightweight nylon stuff sacks are often used for bear bags, but they can be made simply of a large enough square or rectangular piece of cloth or tarp with the food items placed in the center of the tarp and the corners brought up and tied around with rope. The rope is then used to tie the bag in the air where it cannot be reached from the ground or from a tree by a bear. Often this is done by tying another length of rope tightly between two trees or other tall objects. In problem areas, a bear bag should be at least 12 feet (3.5 m) high and 10 feet (3 m) from any vertical support. The counterbalance method, Marrison system, and the Pacific Crest Trail method are a few different techniques to use when hanging a bear bag.
In areas where trash cannot be burned (much of the United States and especially during dry seasons) and no fortified trash containers are available, trash may also be raised in a separate bear bag to keep the food smells from attracting bears or other animals.