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Backpacker Magazine – Online Exclusive

Gear Review: Black Diamond Twilight Bivy Sack

A minimalist-style bivy that separates you from the nasty outside.

by: Joe Flowers

Black Diamond Twilight Bivy (Courtesy Photo)
Black Diamond Twilight Bivy (Courtesy Photo)

The Specs
Price: $150
Weight: 11 oz.
The startled look in my wife’s eyes when I told her I had to sleep outside to test the Black Diamond Twilight Bivy, was priceless. She is used to the occasional backyard campout, but the 27 mph howling wind coupled with the drenching rain in the high 30s made her question my sanity. But I persevered and the four-season rating of the Twilight Bivy was put to the test.

This minimalist frameless bivy sack is a little over six-and-a-half feet long and over two-and-a-half feet wide. One tester reported that it was just big enough for his 6’ 200-pound frame, but for the average person, the fit of this sack is unrestrictive and you can even sit upright while cooking in the morning. Size note: A rectangular Big Agnes Air core fit inside nicely.

The bivy is basically polyester with a special water-resistant silicone nanocell treatment, that is lightweight, but still durable for its weight. (I won’t say waterproof because Black Diamond says it isn’t.) However, I awoke in a puddle after the storm, and was happy to find my down sleeping bag and body dry. And despite the 27 mph wind, I didn’t feel a draft. In later tests, it did just as well in the blowing snow.

Bugs are thwarted by the zippered mesh front that lies underneath the opening/entrance and loops on the outside to roll the screen up. With the bivy completely enclosed, there is no stuffy feeling thanks to the breathable NanoShield fabric which also doesn’t have the fragile feeling of other lightweight fabrics.

A long time ago, I got stuck in a bivy when the zippers malfunctioned (and my buddies still make fun of me for it). The zipper location on the Twilight is crystal clear and it unzips smoothly with a simple string. This is an important feature if the user hears rustling and doesn’t want to become a bear burrito (I’m guessing, here). I do wish there was some type of glow-in-the-dark bead attached to the zipper though (I’d like to see these on sleeping bags too!). The zipper goes across the shoulders, giving enough head room in the top of the bag to fit a pillow (or small dog). But, the Twilight packs down to less than a 16 oz. bottle, and a true minimalist probably wouldn’t pack a pillow that is bigger than their shelter anyway.

Bottom line: As an emergency bivy for a thru-hiker, or someone who wants to go ultra-minimal, this lightweight bivy sack will please and perform.

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Jan 14, 2011

I have an Outbound Hooped Bivy, and I use it for minimalist camping. A tarp and 1 rope normally start it off, and then I crawl into it once I'm covered. I have tried sleeping under the stars and under tarps, but I have been woken up by several different creatures looking for warmth (including a skunk) Explain to your significant other why you need to buy "another" sleeping bag!

Joe Doakes
Jan 06, 2011

A tarp sure is nice to cover all in the rain. Makes setting up a tent, rolling out the sleeping/bivy sack more pleasant. In a pinch, deploy that tarp on the ground, get under, and just get warm and as dry as possible in the bag. Happy camping to you all.

Jim W
Dec 31, 2010

Could not agree more. Bivies, great for an emergency. Stay with a one-man tent for light travels and comfort!

Dec 21, 2010

Bill - that's why you combine them with tarps. An ultralight tarp and bivy tend to weigh less than a tent.

Dec 21, 2010

Take a second and help a fellow BP reader win a trip to Glacier NP:

Bill Weber
Dec 21, 2010

I've never used a 'bivy sack' and I can't see spending that much money for one. They may be great to carry for an emergency but they have a huge drawback. No one talks about how you get into or out of them in a pouring rain or falling snow. You will get soaked and bring the wetness into the bivy sack. You can't undress very easy inside one and where do you put your wet cloths??? I have an older model of a Eureka 'one person' tent. It has room to put your wet things and enough room to change but you get soaked getting into and out of it.


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