A bivouac shelter is any of a variety of improvised camp site, or shelter that is usually of a temporary nature, used especially by soldiers, or people engaged in backpacking, bikepacking, scouting, or mountain climbing.[1] It may often refer to sleeping in the open with a bivouac sack, but it may also refer to a shelter constructed of natural materials like a structure of branches to form a frame, which is then covered with leaves, ferns, and similar material for waterproofing and duff (leaf litter) for insulation. Modern bivouacs often involve the use of one- or two-man tents but may also be without tents or full cover.[2] In modern mountaineering the nature of the bivouac shelter will depend on the level of preparedness, in particular whether existing camping and outdoor gear may be incorporated into the shelter.[3] A bivouac shelter is colloquially known as a bivvy (also spelled bivy or bivvi or bivi).
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