Buying a bivy sack: what you need to know

The underside of the bivy sack is in direct contact with the ground. When the ground is wet, your body weight pushes the material into the moisture. Make sure the water column rating is at least 2,000 millimetres to keep everything underneath dry.

Keep in mind that a sleeping mat and sleeping bag also need to fit in the bivy sack. The sleeping bag should also not be compressed so that the air trapped in the down or plastic fibres can insulate and keep you warm.

Lightweight models are available from 100 grams, heavier ones weigh up to just under one kilogram. They usually differ greatly in terms of functionality: for example, models weighing just 100 grams are to be used for emergencies only, while heavier ones offer additional insulation. All-round models usually weigh about half a kilogram.

Stony ground can be particularly damaging to the underside of a bivy sack. However, thorns from bushes, shrubs and cacti or pine needles can also damage it. It is therefore worthwhile buying a bivy sack with a reinforced base.

In regions and countries with a particularly high number of insects that transmit diseases, a bivy sack with an integrated mosquito net is useful.

Some models have ventilation panels. This can be helpful when travelling to warm and dry areas. They are less suitable as an all-round model because moisture can easily get in.

When buying a bivy sack bag, pay attention to the fact that all can be completely closed with a robust zip – except, of course, the head area. Cord and Velcro fasteners are not waterproof and let rain in, and also mean that water from the ground can seep in. It is important to note that the zip of your bivy sack should be on the same side as that of your sleeping bag. This makes it easier to get in and out, and to ventilate.

Some models have poles, similar to tents. However , these are only for the headrest of the bivy sack. The poles create some space around your head. Because of the additional poles, these bivy sacks are heavier, but offer more comfort and if they have an integrated mosquito net, they also better protection.

A bivy sack is similar to a sleeping bag and although it has no insulation, it can still be used instead of a tent. You slip your sleeping bag into the bivy sack. This extra layer protects you against wind and rain and keeps the heat in.

A bivy sack is used for camping without a tent. They are lightweight and have a small packing size – ideal for people who want to travel with a lighter backpack. There are particularly lightweight models for emergencies. Similar to the golden emergency blankets, these emergency bivy sacks protect against hypothermia and hyperthermia.

A sleeping bag and bivy sack are like down jacket and waterproof jacket: the sleeping bag provides warmth, the bivy sack protects against wind and moisture. A bivy sack performs the same function as a tent, offers less storage space, but is lightweight and compact.

Bivy sacks keep the heat in. A tent offers a larger space, but it also distributes heat more quickly – a bivy sack keeps heat close to your body and is therefore warmer than a tent. However, bivy sacks are less comfortable.