what is a bivy bag
A bivouac sack (in red) covering a man within a sleeping bag in Benediktenwand, Germany. Rock climbing bivouac in Yosemite National Park. A bivouac sack (also known as a bivy, bivvy, or bivi) is an extremely small, lightweight, waterproof shelter, and an alternative to traditional tent systems.It is used by climbers, mountaineers, hikers, ultralight backpackers, soldiers and minimalist campers. bivouac sack (in red) covering a man within a sleeping bag in Benediktenwand, Germany. Rock climbing bivouac in Yosemite National Park. A bivouac sack (also known as a bivy, bivvy, or bivi) is an extremely small, lightweight, waterproof shelter, and an alternative to traditional tent systems.