Bivy/Bivouac

A bivy (short for bivouac) is a minimalist, single-person emergency or ultralight shelter used in camping and mountaineering. It typically consists of a waterproof and breathable fabric sack or small tent-like structure that provides basic protection from wind, rain, and snow while taking up minimal space and weight in a backpack. Bivies are popular among ultralight backpackers, climbers, and military personnel who need quick, temporary shelter without the bulk of a traditional tent, though they offer limited interior space and comfort compared to standard camping shelters.