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REI Thaw Bivy

The Thaw Bivy has been discontinued. If you're looking for something new, check out the best bivy sacks for 2022.

photo: REI Thaw Bivy bivy sack


1 review
5-star:   0
4-star:   1
3-star:   0
2-star:   0
1-star:   0

An older bivy with some versatile features that I haven't seen in others.


  • Waterproof
  • Bug proof
  • Lightweight
  • Increases warmth
  • Cinches down tight


  • Keeping rain out of head hole can be tricky

Setup: Since there are no poles or stake out points, you just throw the bag on the ground and crawl in.


Weather Resistance: Keeps water out really well except for the hood hole. It works well as long as you position yourself right, cinch tight, and don't toss and turn too much in your sleep. If the sack is used in conjunction with a small head tarp, there aren't any issues.

Ventilation: The hood hole offers great face ventilation. The bag itself is impermeable 2/3 the way down.

Room: There is ample room in this bivy for a thicker cold weather sleeping bag with lots of loft. I once stuffed 2 sleeping bags and a sleeping pad in it on a really cold night. It was a squeeze but I stayed really warm.

Packability: Packs down to 5" x 11". It weighs 1lb 12oz.



Ease of use: The bivy has 4 zippers so no matter what way you are turned, you have zippers to get you in and out of the bag. For added protection, you can snap the bag shut as well. The hood has a good head cover that leaves your face exposed. You can roll the hood up and snap it down to give you a nice opening. There is a cinchable bug net that snaps over the head hole. The hole works very well at keeping condensation out of the bivy.



In the winter I use the bivy for added warmth. I actually liked it better than my OR bivy for winter use because the OR bivy has the screened opening behind the head, therefore when you breath, you breath on the roof and  it condenses in the bivy. With the THAW, it all goes out the hole keeping you dry. You can also cinch the hole down to 1".

Even though it is really gaudy, it is my favorite cold weather accompaniment.  I throw a thin mylar summer windshield sun blocker inside with my sleeping bag and it locks in an enormous amount of heat.

Construction and durability: All seams are still great after all these years. Some of the waterproofing membrane around the interior of the hood is just starting to go. I'm sure this bag is 20+ years old however.


Conditions. I've used the sack in -40°F (-40°C) to summer camping on rainy nights. I've had the sack for three seasons now and plan on holding on to it. Another oldy but goodie. 

Source: bought it used
Price Paid: Free with a used tent purchased online

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