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Mountaineers and backpackers have long been on a quest to find a sleeping tent that is compact, compresses tightly, and is lightweight to carry. The best solution for some is a bivy sack. Original bivy sacks started as waterproof sleeping bags that provided temporary emergency shelter and sleeping space for adventure-seekers. Today’s bivy sacks reflect body heat to protect the body from the elements longer than laying on the ground out in the open. They have the added benefit of being fully sealed to keep out bugs, snakes, and other animals.
Top 3 Bivy Sacks
How to Choose the Best Bivy Sack
Bivy sacks come in various styles, colors, and sizes. Let’s first discuss what exactly a bivy sack is and what to look for when choosing the best one for your next wilderness excursion.
What Exactly Is a Bivy Sack?
The full word is bivouac sack, but everyone calls it the bivy sack for short. They’re basically personal tents, providing warmth and protection from rain, snow, bugs, and anything else that you don’t to be in bed with when you’re sleeping outdoors.
They’re essentially made with two layers. The bottom-most layer is made of a tough, durable, waterproof nylon, like what you would find most tent floors made from. The top is usually made from something more lightweight and breathable because it is made of Gore-Tex fabric.
Some bivy sacks add a little bit of extra room around the head and shoulders, for those who need some wiggle room. Meanwhile, for the more claustrophobic backpackers, other bivy sacks have an opening for the eyes and mouth.
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Bivy Sack vs. Sleeping Bag
Tents range from accommodating just one person, to being able to fit multiple people. They’re usually the best choice if you’re going camping with a large group and you all need somewhere sheltered to sleep.
Tents can still be useful if you’re camping solo. They provide a nice little sheltered “room” to block yourself from rain, bugs, and other elements. They’re also spacious enough to store extra gear you may have brought with you.
Bivy sacks or shelters, on the other hand, are designed to serve the purpose of both a tent and sleeping back combined, but for just one person. They provide a place for one person to sleep while being sheltered and warm.
They’re great for people who backpack frequently through the woods or mountains and either need less weight to carry, or don’t always have large areas available for camping in. A bivy sack gives someone the freedom to basically sleep anywhere and have the shelter they would normally get from a tent.
Backpacking sleeping bags have many purposes. Kids’ sleeping bags are a “must-have” for families with children. Kids’ sleeping bags are lightweight, colorful, and may reflect a child’s favorite characters or celebrities, but they are intended for indoor use. Heavier sleeping bags work best for tent or RV camping to help keep them warm and dry, regardless of the weather.
Bivy sacks were designed for a greater purpose. The idea behind a bivy sack is to fully enclose the body to protect it from the weather and anything else in the wilderness that will bother you while you are sleeping. Mountain climbers, backpackers, and other extreme athletes can’t be unnecessarily bogged down by extra size and weight in the back pack.
Their sleeping system needs to store as tightly and as compactly as possible, while being lightweight. The down side to bivy sacks is that they are confining and not as comfortable, so look at this article for the best sleeping pads to complement them. A one-person dome tent may be a better choice for someone who is claustrophobic.
Bivy Sack Weight and Packed Size
A common saying in backpacking and survival circles is “every ounce counts.” This includes your choice of bivy sack. One of the things you need to consider when shopping for a bivy sack is how much weight you’re willing to add to your gear.
Luckily, a bivy sack is going to weigh much less than a tent would and it is easy to set up. Although most tents weigh between five and ten pounds, even that can become a burden if you’re wearing it strapped to your shoulders for hours on end.
Bivy sacks, on the other hand, weigh only ounces. The larger, more heavy duty ones (especially those with a domed head for extra headspace) will run around 40-50 ounces, while the mummy-style designs will probably only weigh about 15 ounces or less.
Additionally, the heavy duty styles will have poles, roles, and various other accessories which not only add to the overall weight, but they can also add bulk to your pack. Depending on what you need a bivy sack for will determine how much weight and bulk you’ll be willing to carry with you.
Material and Durability
As previously mentioned, the two layers of the bivy sack are made by different types of fabric. The bottom needs to be waterproof and strong, protecting you from the hard, cold ground of nature. It also needs to be able to keep any bugs or vermin from entering your little shelter. Also, as you move around in your sleeping bag, you don’t want the bottom of your shelter to get torn or punctured by the rough surface.
The best fabric to look for regarding the bottom layer is Silnylon (a combination of silicone and nylon). It combines both ripstop durability and strength while also being waterproof.
The top layer of bivy sack needs to be made from something that’s breathable, while also providing shelter from the elements.
The best options for the top tier are:
- Gore-Tex: laminate made from stretched Teflon
- eVent: waterproof, breathable, and fire-resistant
- Toddtex: like Gore-Tex but is also fire-resistant
- Pertex Quantum: Uses a two-fiber thickness that makes it waterproof, wind resistant, and breathable
- Sympatex: Uses wicking technology that allows condensation to escape. Also breathable and windproof
- Powertex: this is a coating that can be applied to any breathable fabric, making it weatherproof
Space and Ventilation
Another important consideration to make when choosing a bivy sack is how much space you’re going to need in one. While most of them are designed to be a tight and compact fit around your body, there are other roomier styles for those who need a bit more space to move around.
Also, if you have a habit of getting claustrophobic, it is extremely important to consider the fact that bivy sacks may not be the best option for you. There are designs that have an open space for your eyes and mouth, but if you’re sleeping somewhere that’s cold and rainy that can sort of defeat the purpose of having one.
If tight spots aren’t a concern for you, you just need to decide how much space and ventilation you need. If you usually go backpacking during the colder months, you need as much coverage as possible from the wet and the cold. But if spring and summer is more your jam, then you’ll need something extra-breathable that also keeps the critters out. Some designs will come with a mesh covering or bug netting over the face to enhance ventilation while making sure bugs don’t come to visit.
We’ve covered waterproofing concerns, but we haven’t yet discussed condensation. One of the downsides of a bivy sack is because of the tight quarters, condensation tends to build inside, making your sleeping arrangements somewhat damp. Especially on cold nights.
A lot of the condensation will build as a result of your own breathing, as well as any sweat you produce while sleeping. While you’re shopping, look for a bivy sack that is made from breathable materials and offers a lot of ventilation. This will go a long way in limiting the amount of condensation buildup.
Also, once you have your sack, make sure any moisture that you exhale goes out side of the bivy sack. If extreme cold temps or bad weather have you closed up tight, try just unzipping one small hole near your face.
Another thing to try is wearing less layers when sleeping. The more you wear, the more you’ll sweat, which could be counterproductive and make you colder instead of warmer.
Comfort and Warmth
Above all you want something that’s both comfortable and that will keep you warm. But what’s comfortable for you and what’s comfortable for someone else will be completely different. Some people prefer being bundled up like a burrito and sleeping in tight quarters. If that’s you, you’ll love the bivy sacks that wrap you up like a mummy. While someone who likes to have some wiggle room may prefer one of the tented styles.
As far as warmth is concerned, what you need depends on where you intend to sleep with your bivy sack. Many options offer year-round protection, while some of the heavier duty ones can offer protection against temps as low as 10 degrees Fahrenheit.
How much you’re willing to spend is equally as important as everything else we’ve discussed. If you’re on a budget, decide how much you want to pay for a bivy sack, and look for all the necessary features that fit within that price range.
However, if you want performance above price, then take your time to weigh each option against what you need a bivy sack for and go from there.
Being designed for the minimalist backpacker, most bivy sacks provide them most basic of features. Not many bivy sacks will have extra features or accessories, as they’re designed to take up as little space as possible.
Probably the only accessories you may need with a bivy sack is a sleeping pad for comfort and a strap to secure the pad in place.
Our Favorite Bivy Sack Reviews in 2020
The Tact Bivvy is probably the most lightweight option you’ll find out of all the bivys on our list. It offers 100% waterproof coverage, is incredibly durable, and is backed by Tact’s 6 month “any reason” money back guarantee. Its weather protection can not be matched and is considered by many to be one of the best bivy sacks, if not THE best.
The original version was made in bright orange, but this new 2.0, updated model comes in tactical green.
Made from a thermal space blanket material called HeatEcho reflective polyester film, this bivy cover easily reflects 90% of your body’s heat back to you making it great for extreme weather conditions. This ultralight bivy sack only weighs 4.8 ounces, so you’ll barely know you have it until you need it.
This is probably the best product to hold onto for emergencies. Keep it in your car in case you ever break down or get into an accident, or even keep it in the house for those times when the power goes out in the middle of winter. Instead of sleeping under hundreds of blankets, just wrap this around yourself.
Because it’s so lightweight, it’s also a great option to have in your survival pack when you go hiking in the mountains. If you must stay out an extra night or you get lost, at least you won’t have to worry about being cold. Additionally, this can also work as a sleeping bag liner for extra warmth. As the best overall bivy, this could easily be paired with any other bivy sack for extra warmth and protection.
This bivy comes with this own drawstring carrying bag and weighs only about 4-5 ounces, so you can take it with you anywhere you hike or travel. It’s great for emergencies, especially it’s bright orange color that offers visibility incase any rescuers are searching for you. It’s heavy duty and tear-resistant and returns about 95% of your body heat back to you.
Use this as an emergency cover or take it on your regular camping trip as a sleeping bag liner to help boost warmth. Weather you decide to go with the Tact or for this cheaper option, you won’t regret your choice.
This could also easily serve as a companion to any other bivy tent or sack you decide to buy. Since it’s roughly the size of a soda can or water bottle, it’ll easily fit anywhere without adding a lot of weight.
Sleep warmly and safely in this 3’ x 7’ lightweight emergency sleeping bag with heavy-duty fabric. It’s aluminized with PE material that reflects body heat to create warmth and it weighs only 5. 8 ounces.
It’s tear-resistant and reusable. It comes in a high-visibility orange color and stores in a drawstring carrying bag.
Probably one of the most advanced bivys around, the Outdoor Research Alpine Bivy is made of ripstop nylon with the bottom also having Hydroseal with anti-fungal coating. Everything is fully seam-taped, waterproof, and breathable.
Outdoor Researchy's Alpine Bivy has straps inside to hold down your sleeping pad, as well as five stake loops and one guy line loop for extra stability. And there’s an internal mesh pocket for all your small valuables.
This bivy shelter is a great option for those times you want to go on a normal camping trip, but you don’t want to drag out the tent with you. Outdoor Research created what they call a "GoreTex top", which is breathable, and you’ll be protected from bugs, storms, rain, snow, etc. This bivy offers you everything you could ever want in a bivy, and so much more.
Seal yourself up tight in this bivy with 3-layer Gore-Tex respiration-positive fabric. The floor is made of nylon and is hydroseal coated to be waterproof.
The Alpine Bivy has a single overhead shock-corded Delrin pole and end-opening zipper with a wide storm flap. It’s tall enough for thicker mats for a comfortable night’s sleep.
The beauty of this military bivy system is that it’s not just compact but the pieces are interchangeable, giving you’re the perfect warmth and comfort no matter where you are.
The entire pack together weighs 8 lbs, which can be a lot depending on where you’re going, but it offers so much in the way of warmth and protection you may find yourself sacrificing something else in order to include this in your gear.
It’s interchangeable and versatile nature is great, especially if you’re in an area where the climate changes a lot. Some nights you may only need just the cover, or one of the mummy style pieces, while other nights you’ll need all the components together.
Another great feature that these military bivy sacks provide is extra boot room, which is great when nature calls in the middle of the night when you’re sleeping. You can easily sleep with your boots or shoes on and you won’t have to fumble with trying to put them on at one o’clock in the morning.
Have confidence in your gear with this bivy that is standard military issue.
It includes the mummy style patrol bag, black mummy style intermediate bag, weather resistant camouflage Gor-ex bivy cover, and a 6 or 9-strap compression stuff sack.
It's even great for extreme weather since the temperature range it can handle is about 50°F to -50°F
All seams are taped sealed for extra protection and durability, and the tent features a roll away mosquito net, keeping pesky critters away while allowing for ventilation. There’s even enough room in here for your backpack, so you can keep everything safe while you sleep. With extra ventilation and breathability, this is a great option to use year-round.
The Snugpak is an excellent choice of a 1-person bivy with full length side zipper that stands up to severe weather. It’s breathable, yet highly waterproof and even has a waterproof floor. It includes lightweight aluminum poles that create a self-supporting canopy.
It also has a roll-away mosquito netting in front of the hood and a meshed ventilation section at the back.
This tent is the perfect choice for all seasons with a ventilated roof mesh offering full coverage for rain, flies, and more. The large zippered door offers easy access, and it includes three bundles of rope and fourteen heavy duty stakes to keep the shelter secure in strong winds. This is a great option for all your hiking and camping needs.
Go mountain climbing or hiking in spring, summer, or winter, and you’ll be safe, secure, and comfy through it all. This bivy has the best to offer in design and breathability, as well as protection.
Do your mountain climbing or backpacking three seasons of the year with this bivy that is perfect for summer, as well as colder temperatures during fall and spring.
It has a ventilated mesh roof and a full-coverage rain fly. It comes with three bundles of strong cord and 14 heavy-duty stakes.
Stylish and colorful, you’ll be the envy of all the campers while you’re sleeping safe and snug inside this personal bivy sack. It even comes with an inflatable pad for added comfort, so you don’t need to buy your own. You’ll be so comfortable you might just think you’re sleeping in your bed at home rather than out in the wilderness.
This bivy is also a great option for hitchhikers who prefer to live on the road. No need to spend money on hotels all the time. Just carry this lightweight wonder with you, and every night you’ll be sleeping comfortably under the stars. Do you want to watch the stars as you drift off? Just roll the cover away from your mesh window, and you can do so while still leaving the bugs out of the equation.
The only downside is the zipper areas might leak under heavy weather, so if those conditions come up you might want to seek additional shelter. Or, you can buy one of the first two emergency bivys on this list and line the inside of this with it for added protection.
Made from eVent DVSTorm fabric, it’s designed to withstand harsh winter conditions, which makes this this would be the perfect choice for mountain climbers who need sleep snugly and safely on the climb. The super compact design features triple-layered fabric for optimal protection, and yet is extremely breathable to prevent condensation from building up inside.
If you’re not claustrophobic and you frequently hike or backpack through harsh conditions, this would probably be the best bivy for you. One downside is it can be a little up there in price, but it’s worth it for the protection it provides.
This bivy features a full side zipper and draw-cord hood closure for maximum coverage.
You can use this as a traditional sleeping bag, or as a slip cover over your sleeping bag to add warmth and protection. 70% of your body heat is radiated back to you, allowing you to stay warm in as low as 40-degree weather.
Condensation won’t be an issue with this bivy. It’s made out of proprietary, breathable fabric that lets moisture escape while also keeping out rain, snow, and wind.
This bivy is made from heat-reflective polyethylene that reflects up to 90% of your body’s heat back to you. It’s the same material that Adventure Medical Kit’s world famous emergency blankets are made from.
The bivy sack is ultra-light, ultra-warm, and seals you into the sack to protect you from the elements.
10. KELTY TRAIL BIVY
Snuggle into this bivy and you’ll be tucked in as tight as a mummy. It’s a bit over-sized, so it fits easily over your head and will accommodate the larger sleeping bags.
Get in and out of the bivy easily with the U-shaped zipper. The fabric is waterproof, yet breathable, and it has a large mesh vented window.
When you know that you will be hiking or backpacking in remote areas, you need to be keenly aware that the terrain before you is uncertain and the weather is unpredictable. It’s great to plan ahead and it’s even better to be fully prepared for any situation that you may encounter. Taking a bivy along that keeps you warm, no matter what the temperature is, will give you a good night’s rest so that you can tackle any challenges that you may face on your trip.
Frequently Asked Questions
What is a bivy bag used for?
A bivy bag is a portable shelter that is waterproof and popular with campers, hikers, and other outdoorsmen. The primary benefit is that it is waterproof and it goes over your sleeping bag. It’s lighter than a tent and very easy to travel with.
Do you need a sleeping bag with a bivy?
Yes, you sleep in the sleeping bag, which is also inside the bivy. However, you only need a bivy if you are expecting rain. Bivy sacks are not needed for rain-free evening.
Are bivy bags waterproof?
Bivy bags are waterproof, which is really the point of a bivy.
Do you need a tarp with a bivy?
You don’t need a a tarp with a bivy but a tarp can help your sleeping experience since it’s another layer between you and the floor.
Does a bivy sack add warmth?
A bivy sack does add warmth, it can add 2-6 degrees F, depending on the evening and how good your sleeping bag is.
Can you sleep in a bivvy?
You can sleep in a bivvy, but they don’t provide much warmth. They do provide some insulation but it is highly recommended to get a sleeping bag with the divvy.