The very word Bivouac, means (a temporary encampment). But in the eyes of the outdoor enthusiasts, it means a temporary encampment in a micro shelter. These new breed of miniaturized tents are extremely small and weigh very little. Some weigh barely over 2 pounds. They will fit easily in a small day-pack and are designed to handle the worst of weather conditions. These are far superior to the old style cotton bivy sacs that were once issued to American military personel. These old bivy sacks were little more than sleeping bag covers. The newer models that are currently being used by the U.S.military are very high tech. These are manufactured using a very grade material and laminated with waterproof breathable fabrics. The outdoor enthusiast market offers sleeping bag covers that are not only waterproof and breathable but can be zipped completely shut to seal off even the harshest of weather conditions. Some models are little more than tiny tents. I have used both types. If a person is claustrophobic then these shelters will not suit their needs at all. After all, they are very restricted as far as room goes. But as a emergency survival shelters, or for use on extreme lightweight backpacking trips, there shelters are hard to Beat.
The quality of these shelters is superb. and the ability to seal them off from heavy rain or snow is very good. I once slept comfortably through a blizzard in northern Michigan a few years back in one of these bivy sacs. The wind along with blowing snow was ferocious that night. By morning I was covered in several inches of snow, yet none of the snow or wind penetrated my small nylon fortress. Many bivy sacs have micro screen netting sewn into them for extra breathability along with offering insect relief. Most of these models can be seal completely off to the outside weather.
I have even slept in the northwoods of America, where the mosquito population is huge and they have proven to be relentless blood suckers. These mosquito’s simply will not let up. I have zipped myself inside the bivy sac and slept thru the night while hundreds of mosquito’s were trying desperately to get at my warm blood. These shelters are by no means inexpensive, although a decent nights rest is worth a great deal. The photographs show various brands and models. All of the brands shown are worth considering. If you are able to deal with this type of shelter. Keep in mind they are small. Try one, you might like it. I sure do.