Bivy Sacks

Good bivy sacks can be your primary shelter, or just a back-up plan when it might rain and you are planning to sleep under the stars. They don't necessarily reduce the weight in your pack, though, thanks to all the new ultralight tarps that are even lighter. The primary advantage is their simplicity. Roll it out and climb in.

Bivy sacks can be a bit confining, especially if you are at all claustrophobic. In that case you might try something like the Bibler Tents Hooped Bivy Sack. With its netting and headroom it is a little like a tent, but still only 22 ounces. There is a full description at the bottom of the page.

Another bivy sack I would like to try is the Black Diamond Winter Bivy Sack, which weighs only nine ounces. Although it may not be technically waterproof, it has had good reviews, even by those who have used it on rainy trips. You can find a full description at the bottom of the page.

The Lightest Bivy Sacks

To keep it really light, try the Adventure Medical Thermo-Lite Bivy. It is really just a high-tech plastic bag (bet they don't like that description). I had my reservations when I first saw it. I thought I'd wake up soaked by condensation, but I have used it on a rainy summer night (with a small umbrella over my head) and I was dry in the morning. It has screened ventilation at the foot of the bag . I especially like the light weight: 6.5 ounces. Also, there aren't any bivy sacks I know of that are cheaper, except one.

The Cheapest Bivy Sacks

My experience with the Thermo-Lite Bivy made me realize that maybe the warnings of bivy sack condensation were over-blown. I have since experimented with simple garbage bag bivies. To try this, get the extra large bags, duct tape the open ends of two bags together, then cut open one end. My garbage-bag-bivy weighs 4 ounces.

I discovered that in a dry climate, I'm only a bit damp in the morning, and dry quickly hiking. These bivies will wear out easily, but you can just throw them out after each trip and make new ones. At less than a dollar, the price is right.

Precautions When Using Bivy Sacks

When using bivy sacks, be careful not to breath inside them. Even the ones that are waterproof and breathable can't handle much moisture. In the morning check inside the sack, and if there is moisture, take a break at some point during the day to turn it inside-out to dry.

Finally, if you have a bivy sack that can be used with either side down, be sure to always use it with the same side down. Small holes that wear in the fabric will allow rain in if they are on top, but usually won't let much moisture seep in from the ground. Just keep the damage to one surface of the bivy sack

The Ultralight Backpacking Site | Bivy Sacks