Mountaineering is well-loved and enjoyed by many outdoor enthusiasts. But it is not a hobby you take on unprotected and without the right gear. To increase your odds of survival and keep you warm while at it, are the bivy sacks. Bivy sacks are well designed to withstand the harsh and extreme conditions the outdoors may have in store.
They are a necessary and worthy investment for frequent backpackers, hikers, cyclists, and campers. Finding the best bivy sack for mountaineering may prove a little tricky, considering the wide range of options available in the market. This article will tell you more about these essential accessories and a buying guide to help you make the best decision.
What is a bivy sack, and why is it used?
Bivy sacks, also referred to as ‘bivouac sack,’ are sleeping bags that are weather protectors and lightweight and work to protect the users from extreme outdoor weather conditions like rain and snow. They were initially designed to be highly compressible and lightweight, making them suitable gear for mountaineering and hiking enthusiasts, especially during emergencies.
With time, these sacks gained popularity among minimalists and ultralight hikers, given their lighter and smaller weight compared to their counterparts.
Nowadays, the bivy sacks are constructed using the most advanced waterproof fabrics. The modern materials are durable and lightweight, so they are well suited for the bivy sacks.
Bivy sacks are ideal for use outdoors with their unpredictable weather thanks to their waterproof characteristics. This cover for sleeping bags was initially designed for bikers, hikers, and climbers that needed protection for their sleeping bags during their multi-day ascents.
Those who frequently go backpacking mainly find these sacks helpful during the hiking adventures that will require them to stay outdoors for more than a day. They also come in handy during long-distance biking trips that will require a lighter weight to allow them to move longer and farther without much fatigue.
Additionally, bivy sacks are made to endure the colder weather that is usually the case when winter camping.
Over time, the manufacturers made these sacks more durable and sturdier, making them an invaluable accessory whose multifunctionality and easy adaptations to different environments were more prevalent.
From their invention, these sacks have since been evolving to suit different user needs like waterproof breathable fabrics and bug netting for enhanced comfort and reduce internal condensation.
Are bivy bags waterproof?
Regardless of your needs, be it the ultralight or the traditional bivy sack model, they are made with two functions in mind: increasing the warming capacity and keeping your sleeping bag dry.
With this in mind, then yes- bivy sacks are available in waterproof options. They are typically constructed of high-grade nylon with a urethane coating that works to make this fabric waterproof. This material is similar to the one used to make tent floors.
The modern bivy sack has its bottom made of nylon material. This ensures that water does not seep into the bag. This feature is useful when you are camping in rainy or snowy areas.
When it comes to the top-tier part of the sack, they are mostly made of ripstop nylon. This material differs from the one used on the bottom by its lighter weight. Some models use the Gore-Tex material that is a laminate material, breathable and waterproof.
Since the bivy sacks are designed to keep water out of your sleeping bag in most instances, you may encounter some problems if the rainfall is incessant. Bivy sacks feature an opening located at the top to allow you to breathe freely. In this case, you may be forced to cover it over with a tarp to prevent the rain from seeping in.
Are Bivy Sacks Worth It?
Sleeping in a bivy sack is more advantageous than using a tent. Firstly, looking for a place to put your bivy sack is much easier than with a tent at night. The bivy sack does not take as much space as a tent would as it is like a sleeping bag. You are only required to unroll the bivy sack and then slip in the sleeping bag and sleeping pad.
Bivy sacks do not require any guy lines or tent stakes to set up and freeze. You can get in quickly and get warm without delay. Moreover, thanks to its waterproof nature, you do not need a groundsheet because the bottom tier is well designed to keep you dry. You can also count on them to increase insulation for comfortable sleep.
Two of the most significant advantages of using waterproof bivy sacks are their packability and lightweight design compared to tents. These two properties attract adventure racers, cyclists, climbers, light and fast hikers who want a lighter weight in their adventures.
Bivy sacks can also be used as emergency shelters for solo winter hikers as long as you have enough insulation and a sleeping bag to get you through the night.
The downside, however, is that these sacks are more confining compared to tents. They have just enough space for one person and few personal items. You will have to expose your backpack and other gear without any cover during the night.
Moreover, these sacks are more susceptible to internal condensation even with waterproof breathable materials. You may be forced to keep it unzipped or opened at night for maximum ventilation and air circulation so your sleeping bag or quilt will with condensation-free and dry.
How much warmth does Bivy Sack add?
Bivy sacks play the role of adding warmth. The manufacturers ensured that these sacks add about 4 to 8 degrees of warmth to the user.
Besides the addition of warmth, these sacks naturally keep away drafts because they enclose your body entirely.
Therefore, these bivy sacks will protect even the restless sleepers tossing and turning at night from the elements.
10 Best Bivy Sack for Mountaineering
1. Go Time Gear Life Bivy Emergency Sleeping Bag
The Go Time Gear Life Bivy Emergency Sleeping Bag is reviewed to be reliable and will surely come in handy in all of your camping adventures. This emergency sleeping bag is designed for ultimate survival thanks to its lightweight and compact design. Moreover, it is made of the highest quality materials for extended durability. It is multipurpose in its functions as you can use it as a sleeping bag, a survival shelter tent, or an emergency blanket.
On top of that, this emergency kit utilizes a patent-pending Para Synch technology paracord drawstring for closure as well as a 120-decibel emergency whistle. The 26um polyethylene material is extra-thick, weather-resistant, tear-resistant, and durable. This kit features a reflective interior that works to reflect up to 90% of your body heat. The edges are seam-sealed to keep out wind, snow, and wind.
- Maintains body heat to keep you warm
- Keep out wind, rain, and snow.
- Emergency kit built to last
- Reflective interior surface
- Seam-sealed edges
- The ventilation could be better.
2. Bearhard Emergency Sleeping Bag
Bearhard Emergency sleeping bag is ideal to ensure that you are always ready for life’s unexpected events such as bad weather when hiking or on a road trip. Unlike other sleeping bags, it is made of durable polyethylene material that is weather-resistant and tear-resistant. This material is also softer and lower noise than mylar. The materials are high performing as you can count on it to preserve up to 90% of body heat, and it is waterproof, so you can also use it as an outer layer for your designated sleeping bag.
Besides that, this upgraded emergency sleeping bag features an added hood that works to protect your head for enhanced functionality. You can choose from the various sizes available, which are still compact enough to fit in your hand. The storage bag is multifunctional with a 120-decibel whistle and a drawstring closure.
- Added hood offer enhanced functionality.
- High-performing and durable materials
- Lightweight and compact design
- Multifunctional storage bag
- The ventilation could be better.
3. S.O.L. Reflective Escape Bivy
Thanks to the S.O.L. Reflective escape Bivy, outdoors mountaineering and hiking can become your favorite hobbies. This Bivy is designed for survival as it reflects up to 70% of your body heat to keep warm and prevent heat loss in frigid temperatures. It comes with a hood with a drawstring closure and waterproof seams to protect your head and keep out all the elements such as rain, snow, and wind.
What’s more, you can count on this escape bivy to increase your odds of survival when camping. It is lightweight with a compact design, so you need not worry about the extra weight. It features a tear-resistant and soft material that will last you for seasons to come. This Bivy is versatile in its uses as you can use it as an emergency blanket or a sleeping bag on multiple adventures.
- A quiet and tear-resistant material
- Traps warm air and prevents heat loss
- Waterproof seams and drawstring
- Lightweight and compact
- The sizing could be better.
4. DIBBATU Emergency Survival Sleeping Bag
DIBBATU Emergency survival sleeping bag is designed to keep you warm and alive in extreme conditions outdoors. This portable survival kit works to keep you warm as it reflects and retains up to 90% of your body heat. It is also lightweight with a compact design, making it ideal for hiking, camping, hunting, and mountaineering. You can count on it to protect you from unpredictable weather.
The bright orange color used here has strong visibility during a distress signal. Another thing is, this survival sleeping bag is easy to carry and use. The material used is extra-thick mylar for long-lasting use. You can use it as a sleeping bag liner or a ground cover when you are in extreme conditions.
- Suitable for outdoor activities or emergency shelters.
- Excellent color for signaling
- It keeps you warm and alive
- Compact and lightweight
- It lacks a hood
5. BesWlz Emergency Sleeping Bag
BesWlz Emergency Sleeping Bags is highly recommended for outdoor activities. This two-pack survival gear is conveniently lightweight for the best experience. And you know what, it comes with one emergency survival blanket. The material used is waterproof nylon to keep you warm and dry at all times. The insulating mylar material prevents heat loss and retains up to 90% of body heat. You can use it on its own or as a liner for your sleeping bag in extreme conditions.
Additionally, the sleeping bags are made of P.E. material resistant to wear and tear and comes with lightweight sheets. You can easily fold it into a small package for ease of storage and transportation. The high-visibility orange and reflective silver are great for signaling in case of an accident or extreme weather.
- Tear-resistant, waterproof, and windproof
- Keep the user warm and dry in all conditions.
- Lightweight and extremely portable
- Durable materials
- Built to last
- The ventilation needs some improvements.
6. Utool Ultralight Emergency Sleeping Bag
Utool Ultralight Emergency Sleeping Bag is a great and convenient addition to your camping gear. This reliable and flexible kit protects you from any unpredictable weather any time you are outdoors. It is made of high-quality and extra-thick P.E. material designed for use in emergencies to keep you warm and alive by reflecting up to 93% of your body heat. This prevents you from hypothermia and increases your odds of survival.
On top of that, this emergency sleeping bag is bigger and thicker for the ultimate comfort for a wide range of people. The orange color is well selected for its high visibility, so you can use it to make a distress signal. This sleeping bag is multipurpose as you can use it during mountaineering, hiking, camping, surviving, and hunting in the woods. The bag is durable, compact, and tear-resistant.
- Retains body heat to keep you warm
- Waterproof and tear-resistant
- Very compact and portable
- Extra-thick PE material
- Multiple uses
- It lacks a hood
7. Outdoor Research Alpine Bivy
Outdoor Research Alpine Bivy is an excellent addition to your survival kit. This advanced and upgraded Bivy is designed to be more lightweight than its precursors. This bag features a seam taping to keep out various elements such as rain and wind. Moreover, it employs a waterproof and high-performing GORETEX Respiration positive technology that does not collect interior condensation.
Moreover, a traditional clamshell opening serves to allow you to breathe freely without letting in the weather. This sleeping bag is highly breathable with a no-see-um mesh design. The nylon fabric used is a 40D ripstop with T.P.U. Lamination, which is wear-resistant and durable. This sleeping bag has a compact design making it conveniently portable.
- A traditional clamshell opening allows free breathing
- Seam-taped edges keep out weather elements
- High performing without interior condensation
- GORETEX Respiration positive technology
- Compact and lightweight
- It lacks a reflective surface to keep one adequately warm.
8. Sierra Designs Backcountry BIVY REG
Sierra Designs Backcountry BIVY REG is a creative, attainable, and functional gear. It features a guy-out point below the secondary opening, allowing you to lift the Bivy off your face to increase the space inside and increase airflow- all this to increase your comfort. It also features a secondary mesh panel, opening up for increased airflow if the weather allows. This Bivy is conveniently spacious, ensuring that you sleep comfortably anywhere you are.
Another thing is, this emergency sleeping bag is made of a 20D nylon ripstop top and a 30D nylon ripstop bottom with full taped seams for the ultimate functionality. The material is also waterproof for a better experience. The sizeable u-shaped opening makes it easy to get in and out. This Bivy is very compact and lightweight for easy storage and transportation.
- Large u-shaped opening for easy in and out
- A Mesh panel ensures enhanced ventilation.
- A waterproof and breathable top fabric
- Easy storage and transportation
- Compact and lightweight
- It does not effectively reflect body heat to keep you adequately warm.
9. Interstellar AscentShell Bivy
The Interstellar AscentShell Bivy is well worth your money. This versatile Bivy is made of waterproof and durable materials to ensure you have the best experience. It comes with the seam-taped Ascentshell technology that delivers waterproof breathability. You can use a single-pole to add headspace or do away with it to save weight. The newly-designed side entry makes it easy for you to get in and out.
Furthermore, this Bivy comes with an innovative zipper design with the built-in sombrero, which allows you to sit up and perform other tasks such as packing and cooking without having to step outside. Moreover, this Bivy has a compact design and is conveniently lightweight for ease in storage and transportation.
- Compact and lightweight
- Built-in sombrero allows sit up.
- Seam-taped Ascentshell technology
- Easier and faster in and out
- Newly designed side entry
- Waterproof breathability
- It is too narrow
10. M.S.R. Quick-pitch Pro Bivy
M.S.R. Quick-pitch Waterproof Pro Bivy Emergency Shelter is designed for severe adventurers and outdoor enthusiasts. This shelter is conveniently lightweight, making it easy to store and transport. It is also made of a waterproof, weatherproof, and breathable fabric that reduces condensation to keep the Bivy dry and comfortable at all times.
Moreover, it has a compact design allowing it to fit into small spaces. This Bivy is built to last thanks to the Durable water-repellent coating and the Xtreme shield waterproof coating that lasts three times longer than other coatings.
- A durable water-repellant coating gives it extended durability
- Designed for professional alpinists and serious adventurers
- Breathable and weatherproof fabric
- Lightweight and compact
- It does not effectively keep one warm.
Best Bivy Sack for Mountaineering Buying Guide
Bivy sack isn’t your standard sleeping bag. It’s build to shelter you during an emergency or a small stop while you mountaineer. If you don’t get the best for your needs, you might end up freezing or have a very uncomfortable day out in the cold. Here are the few things you have to keep in mind while weighing your options.
Arguably, how you intend to use the bivy sack should be your priority when choosing one. Will it be for overnight hikes or a mountaineering excursion? Do you need it for camping or long-distance walks?
Many ultralight hikers agree that bivy sacks are perfect for short overnight trips given their lightweight design and that they are small and hassle-free to set up. Moreover, you can use them in all seasons and are generally warmer than tents.
However, because of their small size, these sacks limit your space for moving around. They can only fit one person, and so you will have to leave your backpack and the rest of the gear outside without cover. This is inconvenient for those camping every night for multiple days or on a long-distance bicycle tour or hike.
Breathability and ventilation
Unfortunately, the bivy sack can become sweaty, sticky, and very uncomfortable without the proper ventilation and breathability. Pertex, eVent, and Gore-Tex are some of the best materials which offer enhanced breathability in such conditions.
The cheaper fabrics will likely compromise on either weather resistance or breathability. The bivy sacks that feature more interior space and poles are more breathable than those that directly lie on top of the body. Moreover, the bivies with zippers and not drawstring closures let you manually ventilate on dry nights.
Weight is an essential factor that applies to all outdoor gear. The lightweight design of the bivy sacks is one of the reasons that attracts many people. But if you want lesser weight, you can compare the different bivy sacks available in the market.
They may all be lightweight, but you can find that some are lighter than others. This usually depends on whether they have a hoop for a pole.
The lightweight campers focus mainly on the packed size or weight. If the bivy sack you intend to buy does not spare you some few ounces on the importance of a typical tent, then it is no good even though you may want an emergency shelter that you can throw at the bottom of your backpack, ensure that you look for the lightest sack available.
However, before you make a purchase, ensure that the lightweight bivy you have selected does not compromise other features such as space, breathability, and waterproofing. And if the bivy you intend to buy is heavy, you will be better off going for a lightweight tent.
The comfort of a bivy sack depends on various factors. Besides breathability and waterproofing, size is also another factor that will ensure you do not feel shrink-wrapped in your bivy as you sleep.
For those who are tall, you can go for the sacks over 90″ in length. Those with claustrophobic dispositions and those who shift a lot in their sleep, go for a bag that is 25″ at the feet and 30″ at the shoulders for comfort.
You can opt for the bivy sacks that offer an interior pole for those who find the headroom necessary. These sacks include flexible fiberglass poles, which slide into the hood area, creating more volume around the shoulders and face. The downside is that these sacks are often heavier than the minimal bags.
The bivy sacks with a zipper closure along the side make it easy to get in and out than one with a zipper at the head end.
The space of the bivy sack is as crucial as the weight. It could refer to two things when it comes to purchasing the bivy sacks. One is the room that is inside the sack. This is usually the primary concern if you are to choose between a tent and a bivy sack.
Bivy sacks have enough space for just one person, and this may feel claustrophobic. Some can bear with this inconvenience because of their ease of use and lightweight design. It goes down to your personal preference and if the downside is worth it. It may seem so on the short adventures in dry weather.
Second, you can use space to refer to the room it takes in your backpack. As earlier mentioned, the tiny pack size of bivy sacks is one of its advantages. This applies mainly to those without poles, and they are easier to pack and carry along.
Bivy sacks are snug, making them warmer than tents. However, this feature could result in a problem with condensation. The manufacturers do their best to improve the ratio between water resistance and breathability. This happens to be a common problem on raincoats, among other waterproof gear.
Bivy sacks are essentially sleeping bags, and therefore your breath tends to condense on the inner walls. Higher breathability is the solution to that problem, but it compromises waterproofing. The balance is hard to find. Therefore, these sacks are not recommended for use in heavy rain areas. It would be best if you considered the place you intend to use the bivy sack.
As you might have seen, there is a lot to best Bivy sack for mountaineering than just buying the product. You have to understand what it’s and how it works before choosing it as your best choice. Another thing, the products are quite similar, but their features are various. You have to get a suitable model for your needs to enjoy the total benefits of the Bivy sack you buy. Select a model you trust to give you the best chance for outdoor mountaineering and proceed with your purchase. Good Luck!