Our testers have used the bivy sacks featured in this review in a variety of settings, from a cliffside campsite to a mountain meadow swim to a desert river camp. We’ve waited out unexpected storms at high-altitude camps and taken them rock climbing, hiking, biking, and ultralight trekking. Through field testing and objective comparisons, we evaluate each product on key attributes. If you’re looking for a great value product with weather protection, we’ve got the best options for you to consider.
Our team of hiking and climbing experts field-test the best ultralight gear, including ultralight backpacks, overpack sleeping bags, and ultralight shelters. If ultralight gear isn’t on your radar, our in-depth reviews also feature the best products in the hiking and camping gear categories.
We were very impressed with this bivy sack, so we’ll try to point out its shortcomings objectively. That said, if you’re looking for the toughest, most durable bivy sack, the OR Helium isn’t your best bet. It’s specifically designed as a lightweight version of the more rugged, protective alpine bivy sacks. So if you’re looking for a more rugged option with optimal weather protection, check out the Outdoor Research Alpine AscentShell. In a perfect world, you’d have a dedicated bivy sack for every situation. In the real world, you’ll likely only be able to use one, and the OR Helium Bivy Sack performed admirably in everything we threw at it, from heavy rain to long hikes, without adding too much weight to your pack.
The Piñon Bivy lives up to its name and is ideal for mountain ecosystems: you tie a rope between two trees and tie another short rope to a loop at the top of the bug net, holding the net securely in place. When properly fitted, it provides plenty of breathing room above your face and good air circulation for a good night’s sleep in the woods. The price is affordable, and if the Piñon Bivy suits your wilderness travel style, you won’t be disappointed. On the other hand, if you’re looking for better protection on rainy days, the Outdoor Research Helium Bivy is a great choice that won’t cost as much as other high-end models.
While the OR Alpine AscentShell offers excellent protection from the elements, the dense fabric doesn’t offer much breathability in favorable conditions. Taller folks may find the length too short. Since it’s one of the more expensive options we tested, it’s important to evaluate whether its high-quality construction justifies the high price. If you’re not ready to shell out the cash, the Sierra Designs Backcountry Bivy is a breathable, affordable option. Regardless, the AscentShell is our top pick for inclement weather.
The Pro Bivy is more of a specialist than a generalist. If you need a bivy sack that can withstand heavy storms, check out the Outdoor Research Helium. If you’re looking for a bivy sack for emergencies only, the SOL Escape Bivy is our top pick. However, we think its waterproof fabric, spaciousness, and ease of setup make it a desirable companion for an emergency shelter or ultralight mountain mission.
If you’re heading to a cold, dry climate, the SOL Escape can definitely serve as your primary shelter. However, unless you’re at least 5’11” and 175 pounds, the dimensions are too small and this model can’t be completely folded. While the SOL Escape isn’t quite up to par with premium bivy sacks like the Outdoor Research Helium, it’s a great shelter that can be used over and over again without losing the features that make it so useful.
During our research, we looked at over 40 different models before selecting the top 10 contenders to test. We looked at how well they protected us from wind and precipitation, as well as how well they ventilated and moved moisture from the inside out. We also looked at pack size, weight, comfort, and compatibility with other items. We tested in a variety of conditions, from bogs and snow to rocky outcrops. This review is a summary of what we learned over several seasons of intensive testing, and we hope it will help you make your own choice. For more information on our testing regimen, read our full How We Test article.
This review was brought to you by OutdoorGearLab editors and multidisciplinary outdoor athletes Brian Martin and Brian Smith. A former member of the Yosemite Search and Rescue Team, Brian Martin is responsible for researching, testing, and replacing the team’s gear. This, coupled with a lifestyle focused on a variety of outdoor activities, has given him a deep understanding of the capabilities of various outdoor gear. He is equally familiar with backpacking, backpacking, and mountain biking, and uses his extensive experience to help readers understand the pros and cons of various products for different activities. Brian Smith is an IFMGA/AMGA Certified American Mountain Guide based in Jackson Hole, Wyoming, who spends many nights each year camping in the snow, desert, and mountains. Whether he’s skiing, rock climbing, ice climbing, or alpinism, Brian uses more outdoor gear than most people on the planet. His keen eye for detail allows him to spot mistakes in climbing early and select high-quality equipment that will ensure an unforgettable outdoor experience.
Whether or not to bring a bivy sack depends on many factors, from weight and weather forecast to available space in your backpack. All of these factors will influence your decision. Before you buy a bivy sack, consider the conditions in which you will use it. Mountains in winter? Swamps in spring? Each product we reviewed has unique features that may be good reasons to consider it for your next vacation.
Our goal is to bring you the best products while still providing the best value for your money, especially in terms of performance and value. Our team of experts have put each model through a battery of tests and rated them based on a range of factors. There are likely to be a number of pros and cons to consider when choosing the camper that’s right for you. What are you looking for? If value is at the top of your list, check out our rankings of the best-performing products in your price range. The Katabatic Gear Piñon Bivy stands out for its low cost, lightweight portability, comfort, and breathability (though it will require a tarp and some ropes to make it more waterproof). The Sierra Designs Backcountry Bivy ticks most people’s boxes in this category (lightweight, comfortable, and weatherproof), but it’s not as expensive as most premium models. Or for emergency protection on a budget, the SOL Escape Bivy will give you the extra protection and warmth you need in an unexpected situation, without breaking the bank. As always, we encourage you to find a product that meets your performance needs and budget.
From emergency bivy sacks to ultra-protective models for alpine expeditions, it’s important to have a clear understanding of the features of the bivy sack you’re considering. Does it make sense to have an ultra-light emergency bivy sack and a heavy bivy sack for mountain treks? Whatever your needs, we’ve thoroughly tested these bivy sacks within their intended range (and beyond) to determine their true limits. Waterproof fabrics and the ability to fully zip and close the bag are some key factors that affect its performance.
The most weather-resistant bivy sacks we tested were the Outdoor Research Alpine AscentShell and the Outdoor Research Helium. Both of these bivy sacks are waterproof and can effectively block wind and rain. We believe these two bivy sacks provide the best balance of durability, warmth, and overall protection.
Different types of fabric are best suited for different situations. Completely waterproof materials like Gore-Tex block all rain, but even the most breathable fabrics make it difficult for water vapor produced by sweating and breathing to escape. Ripstop nylon can be both lightweight and waterproof if treated with a durable water repellent (DWR) coating. It is generally more breathable, but since it is not completely waterproof, it is only suitable for light rain. SOL Escape is different in that it creates a bivy sack from metallized spunbond olefin, which is often used as a waterproofing material in home construction. This material provides excellent weather resistance while maintaining some breathability. However, since this option cannot be completely sealed, it provides little protection from the elements.
Some bivy sacks are designed to provide all-season protection and can be used in cold, high-altitude conditions. Other models try to save weight and do not provide a full seal of waterproof shell material around the face, so they are best saved for emergency situations or in moderate rain and temperatures. The bivy sacks with the least amount of protection are usually the lightest options. Just because they can’t keep you warm and dry in a downpour doesn’t mean they don’t have their place. These lightweight emergency bivy sacks are invaluable for quick, easy climbs, long runs over rough terrain, or for quick packing when extra protection is needed.
As with any camping tent, how you use it will affect its weather resistance. If possible, choose a high spot or open space under a tree to provide extra protection from the elements and avoid water pooling during heavy rains. Be sure to check the upper trees for dead branches or “widows’ limbs” that could break and create a hazard (especially during a storm).
When looking for a bivy bag, it’s important to think carefully about what you’re going to use it for. Before you consider weight and pack size, make sure the bivy bag’s features meet your needs. If you’re heading to a high-altitude environment with lots of snow and possible precipitation, you’ll want something that will keep you comfortable for a long time and that will keep you dry. If you’re going on a steep ridge for the day but aren’t sure if you’ll need to set up camp, a lightweight bivy bag may be a better option for emergencies.
If you’re just starting out with ultralight tents, there are some great options on the market that will provide decent protection from sudden downpours or windy nights. The lightest reusable bivy sack we’ve ever tested is the SOL Escape. Most bivy sacks weigh less than two pounds, which is much lighter than the best backpacking tents. Overall, we recommend the OR Helium, which weighs just over a pound. If you’re willing to pay a little extra for weather resistance, the OR Alpine AscentShell weighs around 20 ounces, which is significantly lighter than several models that didn’t fare well in our inclement-weather testing. Keep in mind, though, that some ultralight tents are comparable to heavier bivy sacks but offer significantly more space.
Comfort is always an important consideration for outdoor gear, especially gear you use while sheltering in the backcountry. Spending time in a cramped or uncomfortable bivy sack with bugs crawling around inside it can put you off using it forever. Factors that affect the comfort of each bivy sack include bug protection, capacity (capacity and layout), ease of use, and additional features like gear pockets or straps to secure a sleeping pad.
If you’re choosing a bivy sack because you want a tent that’s lighter and takes up minimal space in your pack, you should expect a smaller interior – but hopefully not too uncomfortable. When evaluating comfort, we compared floor space, ceiling height, and shoulder width. The OR Helium and OR Alpine AscentShell received top marks in this part of our evaluation. Both options feature a single pole, which provides extra breathing room or even enough space to read a book.
Ultralight and minimalist styles tend to have less bulk, allowing for less material. In contrast, four-season models often feature wire loops or tent poles that help add volume, create more face space, and provide a feeling very similar to sleeping under the stars while still providing all the protection of a tent. Sierra Designs’ Backcountry Bivy offers a great combination of size and comfort, for example, keeping the roof away from your face without adding weight. The SOL Escape is a bit tight, but still usable for our 5-foot-11 gear tester.
Ventilation of a bivy sack can be a tricky business. As with any waterproof gear, the better a bag is at keeping out rain and weather, the less breathable it is. How well a bivy sack vents and how much condensation it holds inside is an important factor in its versatility and performance.
There are many human factors that can make for a rough night, even if you are in a special bivvy sack, so here are a few things you can do to ensure your bivvy sack serves you as well as possible. The main problem is that condensation from your breath or excess sweat from overheating can collect inside the sack, creating a “rain” effect when you move or change positions inside it. If the weather is dry, one of the easiest ways to prevent condensation is to keep the zippers as open as possible. Even in heavy rainfalls or for extended periods when full protection is required, we recommend leaving the mesh or zipper “open” to allow condensation to ventilate inside.
If the forecast doesn’t call for dry weather, there are two important things to remember: breathe out of your sleeping bag, and use a sleeping bag and pajamas (or whatever you sleep in, if you have one) that are appropriate for the temperature. If the temperature is unstable or you toss and turn in your sleep (and can’t easily keep your mouth in the opening of your bivy sack), consider bringing a synthetic sleeping bag instead of a down one. Why? Synthetic insulation will retain its insulating properties and keep you warm even if it gets damp or even soaking wet.
If your bivy sack can be secured or has a stand that provides headroom, using these features will create additional air space between your body and the sides of the bivy sack, greatly increasing its ventilation capabilities. Both the Outdoor Research Helium and Outdoor Research Alpine AscentShell have this feature, making them more comfortable than models that have fabric that sits against your face.
No matter what you plan to do with your bivy sack, its packed size matters. Space is always at a premium in our duffel bags, backpacks, and bike bags. Having a lightweight bivy sack that fits into a small backpack is essential. By switching from a tent to a smaller bivy sack, you can save a few liters of space, which can reduce the overall size of your pack or make room for other essential gear. Going even further, if you choose an ultralight bivy sack, you can even pack it down to the size of a soda can, saving a ton of space in your pack.
We measured each product packed in a (usually provided) storage bag. Some models come with poles that can be placed in the same storage bag or stored separately in a backpack. The Survival Frog Tact Bivvy 2.0 tent had the smallest folded size of all the products we tested (2 inches by 4.5 inches), but it felt more like a disposable camping bag because it could easily be torn and rendered unusable (think of a giant leaf bag at the cottage). The Sierra Designs Backcountry Bivy is a more durable and affordable model at 3 inches by 9.5 inches. Finally, the top-of-the-line OR Helium and OR Alpine AscentShell high-performance models measure 4 inches by 12.5 inches and 3.5 inches by 12.25 inches, respectively.
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