Bivi

Bivi, short for bivouac sack, is a lightweight, waterproof cover designed to protect a sleeping bag from the elements. It is essentially a minimalist tent or shelter for one person. Bivis are commonly used by hikers, climbers, and backpackers who prioritize ultralight gear and simple setups. They offer protection from rain, wind, and dew, helping to keep the sleeping bag dry and warm.

The primary advantage of a bivi is its weight and packability. They are significantly lighter and take up less space than a traditional tent. This makes them ideal for minimalist expeditions or situations where carrying a full tent is impractical. Bivis typically feature a drawstring or elastic closure at the head end to seal out drafts. Some models include a small mesh panel for ventilation to reduce condensation buildup inside.

While offering a good level of protection, bivis can be less comfortable than tents. They offer no interior space for gear storage or changing clothes, and the user is in direct contact with the inside of the sack. Condensation can also be an issue, especially in humid conditions. Despite these limitations, the bivi remains a popular choice for those seeking a simple, lightweight shelter solution for sleeping outdoors.