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Black Diamond
Twilight Bivy

3.7 out of 5 stars
10 Reviews



Twilight Bivy

When the wind and rain start to blow during your solo mission, reach into your pack, and pull out the super-compact and lightweight Black Diamond Twilight Bivy. The water-resistant NanoShield fabric seals out the elements as it surrounds your sleeping bag and breathes better than virtually any water-phobic fabric on the market. A zippered opening at the shoulders provides easy access and lets you sit up to stretch your aching muscles in the middle of the night.


  • Superlight bivy built for four-season alpinism and thru-hiking
  • NanoShield single-wall fabric is weatherproof and breathable
  • Frameless construction minimizes weight and packing size
  • Zippered entry with mesh panel for ventilation
  • Item #BLD00Z2
30D polyester [floor] 70D nylon
mesh panel
fully taped
Floor Dimensions
82 x 33in
Floor Space
18.75sq ft
Packed Size
3 x 5in
Trail Weight
9.9oz [packaged] 10.3oz
Manufacturer Warranty
1 year

Overall Rating

3.5 based on 10 ratings

Review Summary

1 Stars - 2 reviews
2 Stars - 0 reviews
3 Stars - 1 reviews
4 Stars - 3 reviews
5 Stars - 4 reviews

Fits Small

Screen reader users: the following list provides a visual scale to illustrate the product fit. Please refer to the heading above for the fit type in text.
Runs smallTrue to sizeRuns large

What do you think about this product?


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5 out of 5 stars

May 7, 2023

Morning joy

I have some old mammut and Bibler Bivy. Mammut does not breathe, and Bibler is bulky and heavy (Both are over 20 years old) I was skeptical if this breathes, and i would wake up soaked, but no! I woke up with minimal moisture in the bivy! It is also well-dimensioned, I am short but bulky and I had a comfy night with my manly and formidable shoulders and beer soked dad bod! Nice to come to this millennia!!

Toni L.

Originally reviewed on

5 out of 5 stars

April 27, 2023

Not an emergency bivy

Some of these negative ratings seem to be confused about the purpose of this bivy. There are plastic bag bivys that are lighter and more reflective of heat and those work great for emergency use. This bivy is if you’re looking to save weight and not pack a tent knowing the weather forecast looks dry. It’s more of a tent substitute. I’m a bit taller than 6’1” and I still fit fine unlike another reviewer that said you had to be 5’8” or shorter. With a pad and a bag inside it will be somewhat tight but you still have a decent amount of space. If you get claustrophobic this won’t work for you as there is nothing structural holding the material up. I used a stick to keep the bivy off my face but there is a mesh area and if you breathe into the mesh you will mostly avoid condensation issues. Set your expectations correctly and you won’t be disappointed.


Originally reviewed on

1 out of 5 stars

December 2, 2022


A bivy is supposed to be able to save your life by keeping you dry. This bivy is not water resistant. Water goes right through it. I was on a thru hike and got caught in a rain storm. My sleeping bag and I both got soaked. I spent the night freezing in the rain wondering if I was going to die of hypothermia.


Originally reviewed on

3 out of 5 stars

July 17, 2022

Small, tight footbox

First the good bits: it's warm (probably adds ~10°F to a sleeping system) and semi-breathable. It should be fairly drip resistant, but I wouldn't trust it alone in a downpour. The floor seams are taped (and the floor feels quite durable; should prevent most punctures to a sleeping pad). The dual-pull zipper for the hood is very nicely engineered. Now, the bad: if you're taller than 5'8", and plan to use this with a sleeping pad (e.g. as part of a quilt system), you'll find it to be too small! For shorter people, a mummy sleeping pad that's <2" thick is probably going to work. As I'm 6' tall, even with a thin klymit pad, I think it's tight in the footbox; with a Big Agnes, it crushes my feet, and it's impossible to side sleep. I plan to enlarge it by about 6" in height; the side/top seams are done in such a way this should be an easy modification.

Eric L

Originally reviewed on

5 out of 5 stars

July 17, 2022

This sack is excellent for adding warmth to a sleeping bag inside a tent or as a stand alone shelter. I keep one in my disaster kit, in case of an unexpected opportunity to sleep in the wilderness.

Loren C

Originally reviewed on

4 out of 5 stars

May 26, 2022

Packs small, waterproof, not very breathable

Title says it all. First are the cons: Sleeping bag was soaked every morning. I would have liked a vertical zipper so I could sit up and adjust my bag without being in the bivy which makes it hard to move around. I had my sleeping pad inside the bivy which made it stiff and hard to sit up at all. Pros!!: However it is great as far as simplicity and super light and small to pack! This is my first bivy..

Sarah N.

Originally reviewed on

4 out of 5 stars

January 25, 2022

Seam seal

Haven't used it yet but I need to know if I need to put the seam sealer outside the bivy or inside and what is the best seam sealer for it.


Originally reviewed on

4 out of 5 stars

January 17, 2021

light weight shelter

I've used it several times
5' 10"

I used this bivy sack on my recent 200k fat tire race in idaho. Overall it worked well but i did struggle with the zipper at times. I wish the zipper opened vertically rather than horizontally across my chest. It made getting in/ out of the bag a pain and I had to wrestle with the hood every time. As far as providing protection to my sleeping bag it worked fine.

Andrew L
5 out of 5 stars

August 22, 2019

Class bivvy

Totally disagree with the previous review - totally surpasses my old Rab bivvy in terms of build quality and breathability.


Originally reviewed on

1 out of 5 stars

June 19, 2019

Realy bad

Functionality of this "nano tech" is really bad. Small rain and I could swim. Me, my sleeping bag and pad were in water. It was not because of my breathing, but really because of the rain. So If you think that this bivy save you, so not. My hike this day started 6 hours later, than I wanted, because of drying my sleeping bag. I do not recommend to anyone.


Originally reviewed on