A bivy, also called a bivouac sack or bivy sack, is a lightweight protection device most commonly used when camping outdoors. It should be large enough to fit over a person's sleeping bag and offer extra protection from the weather. The sack comes in a range of materials and fabrics, but its waterproof capabilities are a big factor when deciding which type to choose. Campers can think of it as a tiny tent for one person and his or her sleeping bag.
When hiking and backpacking, the amount of weight a person is carrying can make a noticeable difference. A bivy can be made from very lightweight material and can weigh less than a tent’s groundsheet. The material should be breathable to eliminate condensation, but also waterproof to keep a sleeping bag from becoming damp.
An excellent bivy should be big enough to allow for additional layering on top of the sleeping bag. It should also have enough room to store some extra gear. The sack should ideally have loops that can be staked down to prevent it from blowing away in high wind conditions.
Some come with an attachable hood, which is usually large enough for a small pillow and some extra tools, such as a flashlight or a water bottle. The hood can also be made from mosquito-resistant material. Alternatively, mosquito-resistant netting may come down over the front of the hood and be attached at the sides with a hook and loop closure or a zipper.
The bivy is an excellent option to add warmth when sleeping outdoors, and it can be found in the backpacks of the most experienced hikers. A more sophisticated product is made from materials such as silicon and GORE-TEX®. It cannot guarantee protection in torrential downpours, but it is shower and rain proof. This device is of the most benefit when some shelter has been found, such as a cave that has heavy condensation.