A canteen is a bottle which can be re-used. Canteens are most used for carrying water to places where water is hard to find. Many canteens can be worn on a belt, or held with a strap, like a purse. They are carried often by soldiers, hikers, and campers. Old canteens were mostly made of metal but newer ones can be made of plastic. The idea of a canteen comes from ancient times when water and wine were carried in bags made from animal skins. 