What is a bivy bag?

The bivy bag (also known as a bivouac, bivi, bivvy or bivvi bag) was first developed as a basic but effective solo shelter for mountaineering and climbing where lightweight and small pack size were vital. The original bivies were little more than waterproof sleeping bag covers that protected users from the elements or could be used as temporary emergency shelters. Comfort has always been sacrificed by users for the trade off for reduced weight and small pack size. Since then, the demands from and technology for outdoor gear has changed dramatically.

The traditional bivy has evolved to include waterproof breathable fabrics and insect protection to help reduce internal condensation and make them more livable in variable weather when increased ventilation is desirable. Other adaptations have seen hooped poles being integrated to bivy bags to create more spacious shelters, making them more livable in poor conditions when you need to stay in them for a longer period of time.

The bivy is a specialist piece of kit and therefore is not going to suit everyone. It now has to compete with ultralight tents and tarps which have all been changed and updated in terms of styles and technologies in order to better meet the demands of the market. There is still a place for the bivy, providing you understand the pro's and cons and it suits your desired use.

Advantages of a bivy

  • Lightweight - compared to a traditional tent, a bivy is often much lighter for the price and protection you get. Ultralight tents and tarps can offer solutions with similar or even less weight, but they will not come close to a bivy on price when they get to a comparable weight.
  • Size - smaller pack sizes allow you to take smaller backpacks then normal which is ideal when moving fast and light in the hills and mountains. The space needed to use your bivy is hard to beat when compared with a tent footprint, plus guy lines. Essentially, if there's enough space to lie down, there's enough to sleep in your bivy.
  • Ease of Use - most bivy bags take seconds to set up. Compared to the time and effort in pitching most tents and tarps this is a huge bonus. Forget fiddling with pole, guy lines, pegs and just roll it out and throw your sleeping mat and bag inside and you're good to go.
  • Warmth - a bivy can significantly increase the temperature range of any sleeping bag so using a bivy can allow you to take a lighter sleeping bag, shaving off more weight. Emergency, foil bivy bags are excellent examples for this and I have slept in my summer bag in unseasonably cold conditions and it was more then warm enough for me.
  • Protection - depending on the type of bivy you choose, they can offer anything from emergency shelter through to rugged, four season use. For the low weight in the worst conditions they certainly out perform the vast majority of lightweight tents and provide a lot of value for money against other four season tents.

Disadvantages of a bivy

  • Space & Comfort - unlike a tent where you can sit up, get changed, cook, store your kit and generally stretch out a bivy is simply a confined shelter. Once you are in a bivy it is difficult to do anything more than lie Add to this your pack and the majority of your things will have to stay outside too.
  • Condensation - is probably the biggest issue with using a bivy bag. Many people think their bivy has leaked but 99.9% of the time it is simply a build up of condensation. If you are doing a single night, using a synthetic sleeping bag or can get some ventilation you can reduce the impacts condensation but it is almost impossible to avoid it altogether.
  • Solo Use - since this is what the bivy was designed for it is hard to criticise it but, if there are two or more people going on the trip there are now loads of lightweight tent options that provide more enjoyable and livable space for the same kind of weight as two separate bivy bags.
  • Prolonged Rain - since space and comfort are already limiting factors to using a bivy, when you are out in prolonged rain it is a long night. With little room to move or chance to sit up the bivy certainly falls well below a tent for comfort, especially on longer trips.
  • Insect protection - very few bivy bags offer an insect net for protection during the night and none are particularly great places to stay when it is rife with midges or mosquitoes. A tent or tarp with bug mesh would be much better options than a tarp in these conditions.

Types of bivy bags

There are three main categories into which any bivy bag is likely to be placed. These are:

Emergency - These bivys are designed to be stored in the bottom of your pack specifically for an emergency when an unplanned bivy is required. They are a semi-reusable, inexpensive, emergency use shelter. They protect you when shelter is needed at vital times, but can't really be relied on to provide regular shelter day after day.

Basic/Unstructured - These are lightweight, simple constructions designed without poles or additional features that increase weight and bulk. They are generally aimed at three-season use so the minimalist models are ideal for most general trips. If your aim is to shed weight and reduce pack size then this is a great option as long as you're not planning on taking it out over winter or during the most challenging weather. They offer protection from the usual three weather in the lightest and smallest packages available. They are also usually well priced too.

Hooped - They typically have some form of pole or wire to create a hoop and keep the fabric off of your face. Made of very stronger materials to increase durability and withstand repeated abuse they will stand up to the elements, year-round. These work across any season and are ideal for winter camping or in situations where protection from the elements is essential. They are generally heavier than basic/unstructured models, but usually more comfortable, especially when the weather is bad, or temperatures drop. These models are normally more expensive than other bivy types.

How to choose the right bivy bag

A number of our staff have bivy bags and use them regularly. We are big fans of this style of camping. You certainly feel a lot more connected with the environment and your surroundings. Being able to look up at the stars from the comfort of your sleeping bag is a pretty unique experience and it is one that everyone should try at least once. Going when the weather is good is the best way to start but, admittedly it isn't going to be for everyone.

Before buying a piece of kit like a Bivy Bag you really need to ask yourself a few questions to decide firstly, if a bivy is the right piece of kit for you, and secondly, which bivy best suits your needs. You should consider some of the following questions;

  • What do you want to use it for? Emergencies, fast and light overnight outings, extended multi-day trips, climbing, solo trips?
  • How frequently will you use it? Occasional, fair weather trips? Regular three or four season use? Rare, emergency situations?
  • What kind of conditions are you most likely to encounter when using it? Is it for use on exposed mountain summits or sheltered glens or forests? Do you need insect protection?

There are ways to make a bivy trip more enjoyable so it's important you give some thought to your set up.

Consider your choice of sleeping mat and sleeping bag. Using a pad that matches your trip and the bivy you have decided to take. The lighter model bivys are best coupled with lighter pads, while four-season and winter bivys are best combined with a warm and durable model but in either case it needs to be able to cope in the terrain and conditions you're likely to encounter.

As you would normally, pair your sleeping bag with the conditions forecast but also bear in mind the size of your bivy. A huge warm sleeping bag with loads of loft may not fit in some of the more streamline, snug bivy bags. Another area for consideration is the down vs synthetic, especially with the condensation and potential precipitation you're like to encounter.

Finally, think about a tarp with your bivy set up. The use of a tarp can create more of a shelter from the elements where you can cook, sit around and generally be more comfortable. I find that it is worth the weight penalty when rain is forecast or I'm going with others on a trip as it makes for a good communal space.