Borah Gear Ultralight Bivy Long-Term Review (100+ Nights)


  • The Ultralight Bivy from Borah Gear is an impressively light and breathable water-resistant bivy with bug netting over the face area.
  • I’ve tested both the Ultralight and Cuben versions over 100+ nights while backpacking and bikepacking. I use it alone on clear nights or pair it with a tarp in bad weather.
  • I love that it packs down to almost nothing while keeping out bugs, drafts, and light water and protecting my sleeping pad.

Let’s get this confession over with: I originally bought my Borah Gear Ultralight Bivy mainly because I don’t like bugs. Whether it’s mosquitoes in the mountains, spiders in the forest, or scorpions in the desert, I always sleep better when I know the creep-crawlies can look but not touch.

The stars do make a lovely ceiling though, and at some point my forays into lightweight gear made tentless adventures inevitable. On fastpacking trips in the Sierra or while bikepack racing in Idaho, ditching the weight and awkwardness of tent poles was just too tempting. I looked into waterproof bivvies and tarps, but found myself gravitating to this seemingly less useful water-resistant bivy.

Two bivy sacks at mountain campsite at sunrise
Perfect for fastpacking the Tahoe Rim Trail in typically clear summer weather (we carried a tarp just in case)

Initially I worried the Borah Gear bivy might be too niche to be part of my regular setup, but it’s actually grown more useful the more time I spend with it. In good weather it’s a warmer and bug-free alternative to cowboy camping at a shockingly light weight. In bad weather it pairs with a tarp for all the weather-resistance of a tent for many ounces less. Its versatility is one of its biggest strengths.

I’ve spent over 100 cozy nights in my Borah Gear bivy, and my husband has spent almost as many in his. In this review I’ll share how I use this interesting piece of gear, why I find it so incredibly useful, what I love about it, and a couple things that could be better.

This bivy is truly tiny when packed!

Ultralight Bivy vs. Cuben Bivy

Borah Gear offers this bivy in two versions:

  • silpoly floor, called the Ultralight Bivy
  • DCF floor, called the Cuben Bivy (Cuben being the older name for DCF, or Dyneema Composite Fabric)

The weight and price of each varies based on the upper fabric, bivy size, and zipper type, but the DCF version is approximately 0.75 oz lighter and costs roughly $70 more.

Which version am I reviewing? Both, actually! My original bivy was the Cuben version, and it’s the one you see in most of the pictures in this review. But after nearly 100 nights the zipper eventually gave out, and when I inquired about a repair Borah Gear instead offered to sell me a replacement bivy at a steep discount. Given that the silpoly version is only 0.75 oz heavier and considerably cheaper, I decided to try it.

Testing out my newer Ultralight Bivy, which I like just as much as my older Cuben version

I’ve used the Ultralight Bivy for a few dozen nights so far, and my experience has been just as positive as with my original Cuben Bivy. The design is identical and the weight difference is completely unnoticeable to me. They both pack down to a tiny size, in fact the silpoly version is smoother and slipperier and seems to fold down even smaller. I’m very pleased with it so far, and it’s the version with best value for money in my opinion.

Most of this review applies to both versions, so I won’t always specify which one I’m referring to. In my experience the only real differentiating factor is whether you want to spend another $70 to shave three quarters of an ounce.

Ultralight bivy on left, Cuben bivy in middle, 1 liter bottle on right. The bivvies are folded up into slightly different shapes here but their size is overall very similar.

Borah Gear Ultralight Bivy Overview

Price: $112 (chest zipper) or $117 (side zipper) for silpoly bottom and Argon67 top

Weight: 5 oz (chest zipper) or 5.3 oz (side zipper)

My Rating: 4.5 / 5 stars

For more info and to purchase: Borah Gear website

Review Summary: At just 5 ounces this insanely light bivy offers fully enclosed bug protection plus water resistance while still being fairly breathable. I love it for warmth and bug protection on ultralight missions in clear weather, or for extra protection from bugs or rain when paired with a tarp. It’s a surprisingly versatile addition to a mix-and-match ultralight sleep system.

What I love:

  • Absurdly light and small, basically just disappears into my pack
  • Roomy and easy to sit up in (with side zipper)
  • So much more breathable than a waterproof bivy (collects less condensation)
  • Bug netting over head area keeps mosquitoes out
  • Adds warmth and blocks drafts
  • Hand-made by small company in Montana with great customer support

Could be better:

  • A bit pricey for those who aren’t counting grams
  • Seams and zippers don’t last forever
Perfect for a bit of extra warmth during dry desert nights on the Arizona Trail

How I Use the Borah Gear Bivy

There are many ways to use this versatile piece of gear. Here’s how I use it most often.

Thru hiking: When hiking the Colorado Trail and Arizona Trail with my husband, we paired two Borah Bivvies with a Six Moon Designs Haven tarp. When skies were clear we just used the bivvies, allowing us each a little more space. When needed we pitched the tarp with bivvies underneath for extra warmth and splash protection.

Solo backpacking: For an ultralight solo setup I’ve been using my bivy with Borah’s silpoly solo tarp.

Bikepack racing: When traveling fast and light by bike I carry my Borah Bivy plus a SOL emergency bivy. As long as the weather is clear I just use the Borah Bivy because it manages condensation so much better. If needed I can slip the whole thing into the SOL bivy, but this setup is only designed for safety and a few hours of sleep at a time, not for comfort.

Thru hiking with partner: Paired with a tarp on the Colorado Trail for a versatile and waterproof shelter system
Solo backpacking: Combining the Borah bivy and silpoly tarp for an ultralight solo sleep system in Desolation Wilderness
Bikepack racing: Packing up camp just after sunrise following a quick bivy during Pinyons to Pines bikepacking race.

Water Resistant, Not Waterproof

The Borah Gear Cuben Bivy is not a fully waterproof bivy sack. You would NOT use this bivy to weather a mountain storm on an alpine climb, or even as insurance against overnight showers while backpacking. In both of those cases, you would end up wet and miserable.

This bivy is water resistant. What does that mean exactly?

The bottom is made from either silypoly or DCF and IS waterproof. This means you can plop it down on damp ground and not worry about water soaking through. It’s essentially an ultralight ground sheet.

The top from the chest area up is bug netting, which is obviously neither waterproof nor resistant. It is, however, mosquito proof.

The rest of the top, from the chest down, is water resistant but not waterproof. If you’ve ever spent a night in a fully waterproof bivy and found your sleeping bag soaked with condensation in the morning, you’ll appreciate the breathability of the water-resistant fabric. The downside, of course, is that you can’t use this bivy as a standalone shelter in the rain.

If it IS raining, you can pair this bivy with a minimalist tarp and still have one of the lightest bug proof and waterproof shelter systems available. The waterproof floor and water resistant top add considerable warmth and protection in wind or heavy rain. This means you can get away with a smaller and lighter tarp, or a less perfect pitch, while still staying dry.

Some condensation is inevitable, as you can see here from the frozen moisture inside my bivy, but the breathable water-resistant fabric manages moisture way better than a waterproof bivy.

Customization Options

Like many small gear manufacturers, Borah Gear offers some handy customization options.

Chest Zipper vs. Side Zipper

The standard chest zipper goes only across the chest, where the bug net top quarter meets the bottom three quarters. This requires a bit more wriggling to get yourself in and out.

The side zipper, available on either the left or right, extends down the chosen side for 20 inches. This makes it a bit easier to get in and out, or sit up and drink coffee in bed.

The side zipper adds a whopping 0.25 ounces, so if you are a gram counter in the truest sense you’ll probably want the chest zipper. Another consideration is that side zippers may be more likely to fail due to the curved section (this is where mine first started having problems).

For me the side zipper is worth the drawbacks. I get cold easily and spend a fair amount of time sitting in my bivvy at camp, snuggled into my sleeping quilt to stay warm. When I bought my second bivy I chose the side zipper again, even though it was the part that failed first on my original bivy.

Woman in bivy sack drinking coffee on bikepacking trip
The side zipper makes it easier to sit comfortably while enjoying coffee in bed.

Long, Wide, or Custom Sizing

The bivy comes in standard or wide width and standard or long height, so four combinations. Fully custom sizing is also available if you contact Borah Gear.

My standard width and standard length bivy is quite roomy for me, but I’m only 5’5″ and 120 lbs. My husband is 5’7″ and has a much broader build than I do, but he’s also fine with his regular size bivy.

Design and Features

Floor: This is essentially a waterproof ultralight groundsheet. It’s been durable for me so far, both the silpoly and DCF versions, but I do try and clear away any sharp bits before putting it down.

Zipper: Works well and easy to use. Consider adding a loop of paracord as a zipper pull to make it a tad easier to find when fumbling in the dark. If it starts to get sticky (normal after heavy use) try a zipper lubricant. If it stops closing behind the slider (also fairly normal) try using pliers to pinch the back of the slider as shown in this video. The zipper on my original Cuben bivy did eventually give out at the curved area and no amount of lubing or pinching would fix it. I contacted Borah Gear and while they don’t offer repairs, they did offer me a steep discount on a new bivy.

Picture of Borah Gear label on bivy

Upper fabric: Water resistance works well in fog or slight drizzle. Fairly breathable, though some slight condensation does gather.

Top bug netting: Keeps the bugs out, as advertised. Comes with a loop that can be used to pull the netting off your face for comfort and better mosquito protection. I rarely use this (requires a trekking pole and/or precise campsite location), but I am a side sleeper and usually sleep in an insulated hood so the netting rarely touches my skin. I imagine back sleepers would appreciate this way to pull the netting off their face.

Stake Loops (4): I never use these, but if you’re leaving camp for a while or sleeping in strong wind I can see them being useful.


Despite its light weight and seemingly delicate construction, I had zero durability issues for the first ~50 nights or so. Like all lightweight gear I think some care is a good idea, but the construction seems solid.

After heavy use on the Colorado Trail and Arizona Trail, our bivvies did start to show a few signs of wear:

  • Zipper started opening behind the slider and getting stuck at the curved corner. I was able to solve this, temporarily at least, by lubricating the zipper and using pliers to compress the back of the slider slightly (apparently it’s normal for this gap to widen slightly with heavy use).
  • I caught the top fabric in the zipper once and ripped a small hole – totally my fault.
  • On my husband’s bivy the seam between the top and bottom, where the zipper attaches, has ripped a hole about 1 inch long. My bivy doesn’t have this issue, but I’m a smaller person and very careful with gear; your mileage may vary.

Overall I don’t think this amount of wear is unexpected for such a lightweight piece of gear.

Weak spot at the seam where the zipper attaches. It’s worth trying to avoid putting stress on this point when getting in and out of the bivy.

Overall I definitely recommend the Borah Ultralight Bivy for folks needing a versatile ultralight sleep system. It’s well-designed and well-made. It may not last forever, but for the price (non-DCF version) I think it’s a good value.

More Lightweight Gear Resources

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About the Author

Hi there, I’m Alissa, founder of Exploring Wild. I’ve had the pleasure of hiking the Arizona Trail, Colorado Trail, John Muir Trail, Tahoe Rim Trail, and countless shorter amazing trails throughout the US and abroad. I love solitude, big views, and a good lightweight gear setup. Learn more here.

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4 thoughts on “Borah Gear Ultralight Bivy Long-Term Review (100+ Nights)”

  1. Thanks for your detailed review. I have an exact same bivy. I’ve used it a few times when the weather was good. I just ordered a ZPacks’ Hexamid Pocket Tarp w/ Doors
    to pair with the bivy in case of rains. I’ve also added a ZPacks’ DCF ground sheet and half a dozen loops to attach it to the tarp although I probably don’t really need it because the bivy’s bottom is made of DCF. But I hope the ground sheet will keep the possible rain splashes off the tarp away from the bivy.

    • On the rocky soil of Arizona I sometimes used a thin polycryo ground sheet. It was more to create a tidy spot for my gear than out of necessity, though I did feel good about also reducing wear and tear on the bivy floor. I often use the bivy without a ground sheet and the floor is still in great shape.


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