CAMPING & HIKING

The Best Bivy Sack: To Bivy or Not to Bivy

Best Bivy Sack
Mark Foster
Written by Mark Foster

The debate continues amongst mountaineers, ultra-light enthusiasts and outdoor lovers everywhere.  The idea of having a seriously competent emergency shelter as a backup “just in case” is very appealing.

When you compare the best bivy sack with light-weight tents, the two options offer similar protection but very different benefits. This is a case where you really need to think your way through your needs, habits and future requirements, and then compare it with what the market offers.

Bivy sacks are popular with ultralight backpackers and climbers as an alternative to ‘traditional’ tents or for occasional emergency shelter.

Early bivies were basically waterproof sleeping bag covers to keep rain off, but new lightweight materials have overcome condensation and other problems associated with the older ones to the point where bivies can now compete almost directly with tents. Given the increased popularity of micro-adventures and quick back-country trips, it’s a good idea to compare models and see which are the best bivy sacks to buy.

The Pro’s of Bivy Sacks

It’s an elegant and neat way to encapsulate yourself for a good night’s sleep anywhere, anytime. If you are a fan of ‘easy come – easy go’ then a bivy is the fastest and easiest way to spend a very comfortable night in places where you cannot pitch a tent.

Pro’s of Bivy Sacks

A bivy is not just small when folded; the added appeal of being able to take advantage of the slightest bit of natural protection, and the fact that you can squeeze into an otherwise inaccessible natural shelter is a very strong motivator for buying a bivy.

You can use a bivy on ledges, in shallow caves, under low-hanging trees, small clearings – places where you just couldn’t pitch a tent. However, each model has its own special strong point, and some bivies are inappropriate in the wrong circumstances or climate.

  • Lighter than tents
  • Perfect for solo hikers
  • Compact when packed down
  • Much easier to set up than the best ultralight tent.
  • It is the least fuss all-in-one outdoor sleeping solution possible.
  • Increases the effective temperature of a sleeping bag by 5F or more, which allows you to carry an ultralight sleeping bag in colder areas to reduce overall pack weight.
  • Waterproof
  • Some models have outstanding winter (four-seasons) performance, often better than small ultralight tents.
  • Some bivy sacks have sufficient head space for you to sit up, sip coffee, read, stow some gear (probably not all of your gear) and wait out bad weather, but it is best kept for trips where you need to be fast on your feet, or move along regularly.
  • They warm up faster than a tent or tarp set-up.

The Cons of Bivy Bags

A bivy is for sleeping, and you are pretty much closing yourself up in a big high-tech bag.

Cons of Bivy Bags

A tent will allow you to laze around having a morning coffee, idly going through your gear and generally stretching out before you face the new day, whereas a bivy won’t.

  • Two is a crowd: unless you really need the extra body heat – and when you consider the weight of two separate bivies vs. one ultralight tent which offers a lot more room, the ultralight tent may well be the better solution.
  • A tent has a lot more floor space. While you can safely wait out sustained bad weather in a bivy, you will be vastly more comfortable in a tent where your movements won’t be as restricted, and you can stow your gear within reach.
  • While most bivies take rain in their stride, your comfort will decrease in sustained rain. Some are completely waterproof, but others have open ventilation access points which must be sheltered from driving rain (a tarp does the job well).
  • Not all bivies offer good bug protection.
  • If you anticipate spending days or hours daily hiding from inclement weather, a tent is best.

Types of Bivy Sacks

There are three general types. Consider the weight, bug protection, convenience and hassle factors of a combination of a tarp and bivy vs. a super-lightweight tent combined with heavier sleeping gear and an extra ground sheet before you buy.

Types of Bivy Sacks

Here are the various models and their differences:

  • Bug Net Models: These are for areas where swarms of insects like mosquitos or crawlies like scorpions might mistake you for dinner. Bug net models are very light and compact but not always water- or windproof, and are best used in good weather, dry climates, or augmented with a tarp or natural shelter. These models are usually priced very well.
  • Four-Season Models: If you are headed into cold or rainy weather, bugs are usually the least of your concerns.  You need a tough, year-round weather-proof shelter, which typically has a pole or frame to keep the bivy off your face. They offer more comfort, but at a heavier weight and price.  A good four-seasons model bivy is more compact and lighter than a small lightweight tent but may cost almost the same.
  • Three-season ‘minimalist’ models: Ultra-lightweight, ultra-simple, no extra features, poles or bulk and suitable for most applications and users. These models are perfect for occasional backpackers who don’t seek out extreme conditions and weather, as they offer protection from most weather conditions and insects, are reasonably priced, and are the lightest and smallest bivies available.

What to Look Out for

The bivy sack will shelter you, but these key accessories will influence your ultimate choice of a great bivy sack, and will also influence your choice between a bivy bag and a tent:

  • Sleeping Pad: Inflatable sleeping pads are great for mountain environments where you may need some insulation from the cold ground; non-inflatable (closed cell) foam pads will also provide a little padding.  The guiding rule is to pair lighter sleeping pads with a lighter bivy sack, but you can also consider pairing a warmer, thicker sleeping pad with a light bivy sack for extra comfort in case of unforeseen cold before you consider using a tent.  However, the thicker the sleeping pad and bedding, the more likely you are to battle condensation inside the bivy.
  • Sleeping Bag: Choose between ultra-light synthetic for hot regions and extra layers as you may need insulation from the cold even in desert conditions. For cool hiking conditions, a down sleeping bag with synthetic finish may prove a great combination with a three-season bag as it has a very high warmth-to-weight ratio.
  • Pillow: If you are concerned about every added ounce, you can cover a climbing rope or hiking boots with your extra clothes, but an inflatable pillow or a fleece-lined stuff sack, turned inside-out and holding extra clothing is much more comfortable.
  • Weather-proof Tarp: This could be the deciding factor between a bivy and a tent. If your tarp is set up correctly, a bivy may be all you need in heavy rain. If you can put one of the open ends of the A-frame pitch against natural shelter such as rock or a bush to protect your bivy from wind-driven rain, it is almost the perfect solution. Don’t compromise when you select your tarp:  choose between super-light with water resistance or weatherproof with a little additional weight.

The Low-down on Bivy Sacks

  • Weight:  The point of getting a bivy is to attain a lighter “total sleeping option” than a tent with equivalent protection. As lighter models have more mesh netting instead of fabric to save ounces, and extra tent poles to add head room will add ounces, you need to balance weight vs. comfort.
  • As an example, a minimalist bivy, ultralight sleeping bag, and a weatherproof tarp is lighter than a four-weather bivy with a ultra-light tarp but will give similar rainy weather protection.
  • Packed Size: Even if light, extra bulk in a backpack can be inconvenient.  If your preferred model has extra poles, see if you can hang them on the outside of your pack.  You can save 5 liters or more of extra space with some bivy sack models.
  • Ventilation:  This is the equation:  the better the rain protection, the more condensation. Learn to prevent condensation by keeping vents open as much as possible. Breathe outside the bivy and don’t overdress to prevent sweating. Work with the features to increase ventilation between your body and walls.
    • If you choose a 100% waterproof material, no rain will touch you, but you will have to deal with droplets of water condensation inside the bivy.
    • Some bivies are made from a 100% waterproof material, but cannot be closed completely, and needs additional protection with a tarp or should only be used in lighter rain.
    • Gore-Tex is waterproof and quite breathable.
    • Ripstop nylon treated with a water repellent (DWR) coating is slightly more breathable but is not waterproof.
  • Roominess:  Floor space is important – some models are up to 7ft long, but extra headroom and shoulder width can turn a shorter model into a great shelter. Ultralight models are shorter and lower to use less material.  Four-season models feature tent poles or hoops to keep wet fabric off you, and if you don’t like enclosed spaces, high headroom will be at the top of your list of requirements.

Now that you’re aware of all there is to no about bivy sacks, here are some of the top rated products in the market.

Top Bivy Sacks for 2017

MSR AC-Bivy Sleeping Bag

MSR AC-Bivy Sleeping Bag

Weight: 15 oz (0.42kg)

Specific Features: The weatherproof outer is supremely breathable, and the zippered mesh panel provides excellent ventilation and freedom from bugs. It is the widest model on our list, strong and great value for money.

Best Use: This is an outstanding combination of low weight, a very small packed size, comfort, room, breathability and weather protection and will suit backpackers, campers and adventurers venturing anywhere.

Description: The All-Condition (AC) MSR Bivy provides excellent breathability due to a bug-protected zippered mesh panel that allows for excellent ventilation. The top and bottom is made of 30D nylon rip stop material and consists of a waterproof 2-ply breathable layer.

The floor is made from a waterproof (10,000mm) thick DuraShield-coated material.

The waterproof outer shell is breathable to prevent condensation from building up inside the bivy sack at night.

The MSR AC-Bivy is incredibly light, has a small pack size and offers great protection under all conditions. The MSR AC is constructed with waterproof fabric but have a ventilation opening that can’t be fully closed, so it is not ideal for torrential rain that lasts for days.

Related:  If you prefer an ultralight tent by the same manufacturer, the 4-season MSR Fury  2-Person tent is a great option as it offers a 76-cubic-foot tent volume, but measures only 7” x 20” when packed.

Outdoor Research Alpine Bivy

Outdoor Research Alpine Bivy

Weight: 30.3oz/859g

Dimensions: Length: 84in/221cm, Max width: 26″/66cm, Peak height: 20″/50cm Size: 15 1/4″x 4″x4″/39cm x 10cm x 10cm,

Specific Features: The patented dual-pole system enables you to set up several different configurations in different conditions.

The anti-fungal coating on the floor is a great feature for humid and wet conditions, and a boon for regular users who don’t have time to let everything dry out perfectly be-fore they move on in the morning.

Best Use: Top weather resistance and comfort makes the Outdoor Research Alpine bivy a choice buy, even if you do pay more. It is well-designed and well-made and won’t let you down on trips to any destination. Even taller users will be comfortable due to the very high floor-to-ceiling ratio.

Description: Rain is kept at bay with a Hydroseal-coated waterproof nylon floor with fully taped seams. Outdoor Research Alpine Bivy can be completely sealedf in very bad weather.

It has a patented dual-pole system which provides one of the roomiest interior spaces available, and increases ventilation in tandem with the no-see-um netting covers. At times when weight is critical, you can leave the second circumferential Delrin pole behind, though you may then have to deal with condensation at the foot end like with other bivy sacks.

The Outdoor Research Al-pine bivy’s internal dimensions are calculated to accommodate thicker than standard sleeping pads and has straps to secure the bedding with an added handy internal mesh pocket.  It is the highest model in our list.

The three-layer Gore-Tex Respiration Positive cover lets warm and moist air escape, while blocking rain while minimizing condensation. It deals with rain with wide storm flaps over the opening and toe-end zippers.

A semi-stiff collar keeps opened zippers apart slightly for perfect ventilation during the night, as does the A-zippered vent at the high-volume toe-end. Stuff sack, 5 stake loops and 1 guy line loop is included.  The OR Alpine is one of the ‘heaviest’ bivy sacks on our list, but is still far lighter than most  backpacking tents.

Related: Outdoor Research makes an excellent minimilast bivy too, and if you don’t need four-season protection you may want to consider the Outdoor Research Helium Bivy.

Outdoor Research Bug Bivy

Outdoor Research Bug Bivy

Weight: 16oz/454g,

Dimensions: Packed size: 14″x 3″x4″/36cm x 8cm x 10cm, Length: 89in/225cm, Max width: 25″/64cm, Peak height: 18″/46cm 18″ high, 25″ wide

Specific Features: Excellent protection against bug and crawlies in a roomy interior, which is provided large no-see-um mesh netting sections.

Best Use: It is what the name says – it offers great bug protection plus moisture resistance. For campers and hikers in arid or humid hot terrain.

Description: Breathable and weather-proof exterior with a tough-wearing Hydroseal-coated waterproof nylon floor. Fabric is kept off your face with one bowed overhead shock-corded Delrin pole passed through a velcro attachment. The pole is supported with additional tension created by lashing the guy ropes tightly.

Smooth zippers allow you to change the configuration for optimum protection against weather, bugs or both. An internal mesh pocket will keep your phone safe, and sleeping pad straps keeps your bed-ding in order.

Outdoor Research Bug Bivy comes with a stuff sack, 3 stake and 2 guy line loops – the support pole section is carried separately. In very hot country we recommend that you use all the guy lines to help keep the bivy fabric off the lower part of your body to improve airflow and make it easy to get in and out.

Black Diamond Hooped Bivy Sack

Black Diamond Hooped Bivy Sack

Weight: 1 lb 10 oz / 695 g

Dimensions: Regular 90” x 35” floor space 21.75 sq ft, long 99” x 35”, floor Space: 24 sq ft. Packed Size: 6 x 19″ / 15 x 48 cm

Specific Features: Comes in two sizes, which is a way to instantly add extra room for gear, but also ensures that taller folks are comfortable and an optional footprint ground sheet can be purchased separately.

Best Use: Minimalist bivy that offers bug- and water protection sufficient for most terrains and weather except prolonged snow camping.

Description: The waterproof and super-breathable Todd-Tex fabric protects against wet weather and prevents condensation. This minimalist single-walled Black Diamond Hooped Bivy Sack has taped seams and comes with a patch kit and some additional seam sealer.

There are no poles, but there is a sewn-in support cable to keep the fabric off your face and improve circulation which is provided by a mesh covered opening.

There is no foot vent, so we recommend that you make full use of stakes to keep the bivy in place when you enter and exit, and improve the room between your body and the fabric to help prevent condensation on the lower part of the bivy sack.

Related:  If you only need bug protection and no weather protection, but love the Black Diamond range, you can consider the Black Diamond Mega Bug Tent.

Aqua Quest Hooped Bivy Tent

Aqua Quest Hooped Bivy Tent

Weight: 2.4 lbs.

Dimensions: 15 x 3 inch

Specific Features: You can choose between highly visible orange and green for your next adventure! The Aqua Quest Hooped Bivy has not only a zippered, fold-down meshed area for bug protection, but a clear TPU window in case it rains but you still want to see out.

Best Use: Aqua Quest Hooped Bivy Tent is a minimalist bag with good weather protection, and is recommended for casual hikes, backpacking and micro-adventures in warmer climate zones.

Description: The single-wall shelter is made from 70D RipStop fabric with PU coating. The seams are heat taped which gives a waterproof rating of 10,000 mm. The breathability rating is claimed to be 3000 gr/m2/day

It features a lightweight shock cord pole which is collapsible to fit into backpacks. This makes the inside quite roomy with extra-wide foot and shoulder areas, and the long length easily accommodates taller folk.

The meshed air vent in the head section is protected with a fold-down fly and works with the ‘Batwing’ stiffeners in the foot area to promote airflow and prevent condensation. The hooped bivy can be pegged down to ensure easy access.

Slight profile adjustments can be made using guy ropes. It comes with 5 light aluminum pegs.

Related:  If you expect a lot of rain, you may be snug in your bivy, but your gear needs protection too.  You can add a low-profile waterproof tarp like the Aqua Quest Guide Sil Tarp to make sure everything stays dry.

Sierra Designs Navassa Bivy

Sierra Designs Navassa Bivy

Weight: 1lb 3oz

Dimensions: 86L x 28W”

Specific Features: A very lightweight bivy with an oversize cut and a U Shape zipper for opening either on the left or right.

Best Use: Sierra Designs Navassa Bivy is very light and portable, but not ideal for very cold conditions, and if it rains buckets for days, the Sierra Designs Navassa bivy is not the best choice as the walls are water-proof but the zippers are not sealed.

Description: The waterproof (18,000mm) minimalist bivy sack is of single wall construction from Drizone 40D nylon fabric, and a 70D Nylon floor with PVC-free seam taping. Breathability is 28,000mm to prevent condensation. Used with either a bug mesh or a storm shield it will provide good shelter in most conditions.

As the zippers are not fully waterproofed, you may need extra protection in heavy rain and you can set up a tarp or shelter under a tree to prevent water leaking in through the seams at the top of the bivy.

Related:  You can combine the Sierra Designs bivy with a lightweight and waterproof sleeping bag for easy, light comfort on your backcountry trips.  Have a look at the 3-season Sierra Designs DriDown Backcountry bed.

Chinook Summit Bivy Bag

Chinook Summit Bivy Bag

Weight: 2 lbs (0.92 kg)

Dimensions: 91″ x 32″ x 22″, Height 17″ (230 x 80 x 55 cm, Height 42 cm)

Specific Features: This well-priced bivy sack uses two DAC Featherlite aluminum poles to elevate the fabric and keep it away from your face. Provides very good height without exposing you to the elements. Excellent breathability and lots of room for movement and gear.

Best Use: Roomy bug and water protection for taller campers in very hot conditions, and suit-able for multi-day wilderness trips and even snow-camping.

Description: Waterproof but breathable fabric top and the ripstop nylon bottom is also waterproof (5000mm) with factory-taped waterproof seams. Chinook Summit Bivy Bag has a roomy foot box, but the aluminum poles at the head section provide a lot of extra space in the contoured hood.

It’s a roomy bivy with some space for gear as well. There are two integrated mesh areas on the front and be-hind the head for ventilation without exposure to the elements. The bivy compresses well, and includes a stuff sack but no tent stakes. Excellent value for money.

Related:  If it’s too hot to sleep iniside a bivy sack and you dont have to worry about creepy crawlies, you can set up a tarp for light protection, though an extra tarp is usually a must-have item on any backpacking trip.

You could consider Chinook’s Guide Silicone Tarp with silicone and an additional 2000 mm polyurethane waterproof coating.

Military modular sleep system 4 piece with Gore-Tex

Military modular sleep system 4 piece with Gore-Tex

Weight: Bivy with patrol bag 2lb 4oz, bivy with thicker black bag 4lb

Dimensions: 24 x 17.9 x 10.3 inches

Specific Features: A very functional ‘layered’ or ‘modular’ sleeping kit which consists of a Gore-Tex bivy sack, a lighter OD Green Patrol Sleeping Bag, a heavier black sleeping bag, and a compression sack.

You don’t have to purchase separate sleeping bags as each module is designed to complement the others.

Best Use: Military modular sleep system 4 piece with Gore-Tex is an all-in one system which lets you choose which parts of the system you want to take with you to cut down on weight and bulk.

It is great for backpackers and campers who get to see a little of every kind of weather and seasons, but if you take along the entire system for very cold weather it is heavier and bulkier than other four-season solutions.

Description:This is a four-season system with a canvas bivy and a choice between a lightweight bag on its own when nights are warmer, the thicker black bag for cold weather, or the use of both in very cold conditions by snapping the bags together with built-in clips.

The mummy-type sleeping bags are narrower than standard sleeping bags with a contoured narrow foot section and an adjustable head system, but will accommodate people up to about 6ft tall in comfort. It is made with heavy duty zippers and durable materials.

Related:  If you love to (literally) disappear into the woods and just need a low-fuss waterproof cover for your sleeping bag you may consider the US Army Woodland Camo bivy cover to keep you dry and inconspicuous.

Conclusion

Have you been persuaded by any of out suggestions in this article?  Perhaps both have a place in our outdoor gear cabinet and we needn’t choose between one or the other. What do you think, and what did we miss in this.review?  Add your experience to the comments section below.

ABOUT THE AUTHOR
Mark Foster
Mark Foster

Mark Foster loves to push his limits when it comes to survival in the wilderness. He might go for a 30-days adventure without any food or equipment except for a survival kit and a knife. We should mention that his survival kit has 122 items in it, so he know what he is doing. Mark is working on his book to share with the world all his experience gained during those brave adventures.

  • Sabrina Bell

    Outdoor research’s Alpine is definitely 4-season bivy. I went on a long trip last winter, it rained and snowed – both times I stayed dry and warm. As long as you aren’t claustrophobic, this bivy will keep you protected. An amazing bivy with rock solid construction.

  • Mark Foster

    That’s true. If you dislike being in enclosed places, then by all means get a tent and not a bivy. 🙂
    Some of my buddies use a bivy sack and they seemed to have no qualms being inside, claiming a more comfortable and snuggled sleep. I can’t argue with that – I can even hear them snoring from where my tent is pitched! 🙂

  • Jack Wilcox

    Bought the Military Modular for a winter expedition. A military friend of mine recommended the bivy to me and assured me that I wouldn’t end up neither cold nor wet. Thankfully, he was right! I like the option of removing layers for different temperatures and it is very comfortable. Personally, I prefer my Solo Tent and tend to take that with me on trips instead, but the bivy is a more than capable alternative when you’re running low on space!

  • Mark Foster

    Hi Jack! I agree with you, the Bivy sack is comfortable to use but it’s not for everyone. Most still prefer tents, though. For moderate weather, the bivy will do for me, too.

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