A shelter is one of the central pieces in every backpacker’s equipment. Most often we’re talking about tents – they come in a variety of styles and sizes so that most people can find a suitable one for their adventures. Most, but not everyone.  Sometimes we feel that a tent needs too much space and that it would be nice if we could bring something more compact and light, to serve the same protective purpose while being much easier to carry around.

This is where bivy sacks kick in. They are a minimalist solution to this problem, allowing you to cut weight and save additional space in your backpack. You get a proper overnight shelter which can be used in emergency situations too. They’ve come a long way since they first appeared, and they are now much more reliable and comfortable for you as the user.

Our goal is to help you find the best ultralight bivy sack, so we’ve compiled a list of fantastic bivies, all of which offer different features you may find useful once you’re out in the wild. In addition, be sure to go through the buying guide below, since it will give you some pointers on what exactly to look for when you decide to buy one.

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How To Choose A Bivy Sack – Buying Guide

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Even though a bivy sack is a pretty specific product, there still are some differences in terms of size, weight, comfort and materials used among other things. You should be aware that bivies are smaller than tents, and give you a limited space inside. In turn, you receive much greater portability and practicality. Take a look.

Size and Weight

While reducing size and weight is something manufacturers focus on when designing bivies, it still needs to have enough room for you when it’s time to sleep. When talking about dimensions, there are two things you should think about – how large is the sack when you open it, and how small is it when packed. As you had the opportunity to see, most bivies range between 80 and 90 inches in length, with some being even longer. If you are a tall person, you should definitely go for a longer bivy – otherwise you might not be able to zip it up properly.

Width also varies from one product to another, and it’s different in shoulder and foot area. Length, width and also height greatly influence the comfort you’ll be feeling inside. Some people feel a bit claustrophobic when they start using a bivy bag, so it may take some getting used to. You should also be aware that most products won’t allow you to fit your gear inside, so you may consider getting a waterproof backpack.

Some products come with poles and some don’t. Poles are attached like hoops which pitch the material and form a canopy over you. This gives you significantly more head space, and reduces the feeling of unrest we mentioned because the fabric doesn’t sit on your face when you zip the bag.

When packed, it should take as little space as possible. All products we listed are very small when compressed, but there are still differences between them. If your bivy sack comes with poles, stakes, or heavier materials for example, you can count on it being bulkier. It all depends on what you need and what your willing to sacrifice in order to get the smallest package possible.

In addition to compact package, you also shouldn’t feel the weight of the bag when on a long hike. Weight usually ranges from as little as 1 pound to just a bit over 3 pounds. This is somewhat the top limit it’s allowed to have – if it exceeds it by much you might as well consider getting a backpacking tent. Like size, weight also depends on the accessories which come with the sack. If you decide to cut down on weight, make sure you don’t eliminate anything you may really need when outside.

Material

As with most gear designed to give you shelter and weather protection, materials most often used are nylon and polyester. Their popularity really makes sense – they are lightweight, aren’t overly expensive and give you good weather protection. Manufacturers apply different coatings on top of these materials to boost their performance. This is usually either PU (polyurethane) or TPU (thermoplastic polyurethane).

Basically very similar, these coatings greatly improve the waterproof rating of your bivy, which we’ll talk about a bit later. You will sometimes find “ripstop” in the description for both nylon and polyester. A fabric with this design prevents large rips if the fabric gets damaged, which is a big plus.

In addition to these, some special materials like Gore-Tex are also used on some products. This is a membrane which completely blocks water from coming in, while millions of pores allow the vapor to leave the sacks preventing  condensation. There are many materials similar to Gore-Tex out there, which all have their ups and downs. You should weigh your decision carefully when choosing, so you get proper rain and wind protection.

Warmth

Bivy sacks can help keep you warm by retaining your body heat inside. The efficiency in this department varies from product to product of course, mostly depending on the type of material used. You should check what the other users had to say about this to get a clearer picture of what you can expect, especially if you plan to use it in the snow. Also, consider combining it with a winter sleeping bag or at least bring a blanket for additional warmth.

Comfort

Even though this is not the main focus point of bivy sacks, you still need to get a good rest when you use them. Several factors contribute to this, and bivies are becoming better and better. As we mentioned earlier, check that your new product has sufficient length and width for your body frame. It greatly helps if you have some space above your body too. The design can make your user experience better – whether you can set it up quickly, and if you can easily get in and out of the sack. Finally, waterproofing and breathability are key components of your comfort inside, because it’s not very fun to wake up wet.

Waterproofing

As we mentioned earlier, the waterproof rating depends on the material choice and additional coating. It’s presented as Hydrostatic Head (HH) rating, where a larger value means better protection. Basically, this is tested with a water column pressed against a material and filled with water to a certain level (measured in millimeters). Then its checked whether the material leaked or not over a certain time period. At least a 1000mm is required for a material to be called waterproof, and all of our product greatly exceed this.

The rating is usually not the same for the fly and the floor of your bivy. Floors will come with a larger rating, because the ground can be very wet and the floor is exposed to it for a longer period of time. In addition, it really helps if the bivy sack you’re getting has taped or welded seams. This eliminates the possibility of water coming through the needle holes.

Breathability

This is often pointed out as one of the weak points of bivy sacks. Waterproof materials aren’t very breathable, and this becomes even more obvious with bivies. The air can’t circulate, and you might encounter a condensation problem. Droplets of water form on the inner side of your bivy because the vapor has nowhere to go. For this reason, try to look for products which have mesh panels or special vents which improve the circulation and eliminate this problem. If you choose to get a bivy made of Gore-Tex or something similar, it will greatly increase your comfort in this area.

Intended Use

Most bivy sacks are waterproof, but you won’t be able to use each of them in every circumstance. Some are designed for warm weather and insect protection, while you can also get a 3 or 4 season bivy tent if you plan year round adventures. You need to think about how long you’ll be staying out and the general weather conditions you’re expecting.

Bivies are the best choice for an overnight stay or even a couple of nights, but if you plan a prolonged stay you should consider a larger and more comfortable solution, like a 4-season tent for example. Also, some product will be more comfortable in warmer months, while others will keep you nice and cozy in cold weather but make you sweat when it’s warm. Weigh the options and make a choice which suits your hiking and backpacking style.

Additional features

Perhaps the best extra feature your bivy can have is a mesh panel (or a complete mesh inner layer). This gives you bug protection when you want to unzip or remove the rainfly, while enabling free air circulation. You should look for a sack with this feature, because nobody enjoys mosquitos buzzing and bugs crawling over you. In addition, some products have extra vents which function even when the fly is completely zipped. Some manufacturers include stakes and guylines, which you can use to properly stabilize your shelter. Finally, some things are added to improve your comfort, like small mesh pockets inside or straps to keep your sleeping pad in place.

FAQs

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Q: What Is A Bivy Sack?

A: A bivy sack is a shelter for one person which you sleep in, and serves as a more compact and lightweight alternative to a tent. You can easily take it anywhere, and you’ll always have something to keep you dry and warm at night.

Q: Why Should I Choose A Bivy Sack Instead Of A Tent?

A: This is a great choice if you need something to sleep in, but you want to save space and cut weight when packing. It’s much lighter and smaller than any tent out there. It’s also a good emergency shelter you can set up quickly, faster than most tents. However, keep in mind that because of the size it isn’t very useful for hanging out inside like you would do in a tent.

Q: How Do I Prevent Condensation In My Bivy Sack?

A: As we mentioned when we discussed breathability, you can have less condensation inside if you choose a sack with good design and material choice. Make sure your new bivy has mesh panels, and unless there is heavy rain you should leave the zipper open so the vapor can escape instead of making condensation inside. Like we said, dedicated vents can help reduce the condensation too. Of course, you can always unzip the sack a bit and ventilate it manually.

Q: How Do I Wash My Bivy Sack?

A: There will come a time when you need to clean your sack before next use. Luckily, most bivy sacks can be washed in a machine, but you should always check the label or instructions. Whether you choose to wash it in a machine or by hand, always rinse it off properly. Some can go in a tumble dryer, while others should be left to air dry. In any case, make sure it’s completely dry before packing it, otherwise you may risk mold or weird smells.

Globo Surf Overview

Bivy sacks are an excellent solution if you need a minimalist shelter instead of taking a large tent with you. A bivy can also serve as a backup in your gear, because one never knows. It certainly has it’s advantages and disadvantages, but it’s a fantastic addition to your equipment if you know what to expect. Make sure you go through all the features – only this way will you be able to find the best bivy sack. We hope that our guide made your choice easier. Have fun hiking!

Have you tried a bivy sack that made it onto our list? Did it give you satisfactory weather protection? Was it comfortable to use and sleep in? Please share your experience with us in the comment section below.

Globo Surf Bivy Sacks Reviews

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Thank you for helping me choose a bivy sack. I don't like to carry a tent when I go backpacking because it takes too much space but the bivy sack proved to be an excellent alternative.

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My name is David Hamburg. I am an avid water sports fan who enjoys paddle boarding, surfing, scuba diving, and kite surfing. Anything with a board or chance I can get in the water I love! I am such a big fan I decided to start this website to review all my favorite products and some others. Hope you enjoy!