THE BIVY
Bivies were, and still are, mostly used as emergency shelters by mountaineers. However, some backpackers see them as a viable (and lighter) alternative to a tent or tarp. I was one of those folks.
Bivies have been around for a long time. Basically they are a waterproof envelope or a big bag you put your sleeping bag inside, eliminating the need for a shelter. I bought my first bivy some 30 odd years ago. Designs haven’t changed much since then. Years ago you could get a basic bivy that weighed around a pound. And you could, just like today, get a bivy with an elaborate setup at the “head” end using poles or a hoop to provide a little more room at the top of this most minimal of shelters – you could lean on your elbow and move around a bit. These fancy bivies, just as they do today, generally weighed at least twice as much as the basic bag.