Akula Half Bag.

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A waist high sleeping bag to be used with our mountain parkas as a complete sleep system. In 28°F or 18°F ratings. 

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Full weight chart up soon.

A compact waist high sleeping bag in 28°F or 18°F to be used with our mountain parkas as a complete system for 3 season or high altitude bivouacs.

For more than half a century the climbers of the European Alps have embraced this concept for one or two night forays into the hills. Nunatak has given new life to idea of the historic 'Elephant's Foot' with the Akula. 

High tech fabrics, 900FP down and Nunatak's supreme craftsmanship makes the Akula superior to the crude chopped off sleeping bags of the old mountaineers.

This seemingly odd sleep system combining a short bag with a full strength down parka is so warm and versatile that it has become the Nunatak staff's preferred 3-4 season overnight climbing setup. We leave our arms in the sleeves and simply stick the hands inside the Akula or in the parka pockets.

For sitting or limited space no other system works better, save for maybe the Raku, another Nunatak exclusive.

Another option for fine tuning the Akula Down is an extended single layer fabric 'sleeve' permanently attached to the top edge of the insulated part. Long enough to cover one's head with a scalloped cut that makes the front lower than the back. Two drawstrings: one at the top of the half bag, operated from the inside, and another controlling the top of the sleeve. See here for pics

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Look no further. You found it.

I'm a big guy with broad chest and shoulders, so I wanted to try this since more traditional bags are kinda cramped. Bottom of the footbox gets damp from tent wall condensation, not a problem thanks to the water-resistant down. I pair it with a fleece hoodie +down hoodie +knit gloves.
I like it so much that I just ordered the synthetic APEX version to use during summer months.


Amazing bag!

I used this half bag on my PCT thru-hike in 2003 and it is still (15 years later) one of my favorite pieces of gear. In the Sierra, I paired it with a down parka and in sections that weren’t so cold, I traded out the parka for a lighter synthetic jacket. It was always a welcome treat at the end of a long day in either my homemade tent or for the section when I used a bivy sack. Then being able to wear my jacket on the trail until I warmed up beat the normal shock of getting out of a traditional bag or quilt. I don’t put in big miles like I used to but it even makes a great bag for my five year old who I’m now introducing to backpacking. The bag still has amazing loft after all these years and so many nights of use!



Given the kind of backcountry stuff I do now (mostly backpacking with occasionally an easy alpine ascent) I have long wanted a half bag since I always carry a puffy jacket. The Akula 20 deg was overkill so I asked if they could give me a 35, which they agreed to, reducing the price accordingly. They were most accommodating and efficient and delivered it on time. It is excellent and exactly fits my needs and compresses to not much more than the size of a grapefruit. I've used it 3 times now, the latest being at 5400 feet. I'd strongly recommend it if you have similar needs.

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Akula Half Bag.

Akula Half Bag.

A waist high sleeping bag to be used with our mountain parkas as a complete sleep system. In 28°F or 18°F ratings. 

Product Options
Temperature Rating
18°F - minus 8°C
28°F - minus 2°C
Half Bag Length

The length/user height should allow for adequate low back coverage in sitting position. If in doubt size up and/or perform some measuring before ordering.

Footbox Size
The 38" footbox fit most normal sized feet without footwear.
Top End Closure
Eliminating the top end closure saves 14 grams, but is really only useful if the Half Bag is tucked UNDER the parka.
Shell Fabric

From ultralight (10/20d) over more durable (40/70d) to advanced weatherproofing (7d) 

Liner Fabric
10d Black Taffeta - Lightest, most breathable
20d Black Taffeta - Durable
Down Type
Choosing Hyper-Dry moisture resistant down will help combat the effects of perspiration, misting tents and damp air. Nunatak products made with Hyper-Dry down will have a slight increase in bulk over those made with regular down. A 5% increase in fill weight also occur.
900 Fill Power Goose Down, RDS Certified
900 Fill Power Goose Down, Hyper-Dry, RDS Certified
Down Overfill
Adding overfill can prolong the life of the down, help maintain loft during moist conditions, boost the temperature rating by a small amount and keep the down volume from shifting. Expect a weight increase ranging from one to six ounces depending on the product, the size and the rating.
Extension Single Layer Bivy Sleeve
Un-insulated bivy extension is always matching Akula shell material. Adds about 50 grams.
Roomy to allow for simple tasks inside sleeve; top closure for sleeping draft free; and, with the 7d Robic shell, keeping you dry in situations with heavy dew, mist, light spray. Not seam taped.
Your Measurements
Optional: Fill in the blanks to ensure getting the best fit. No changes will be made to your size selections without approval
Shoe Size 
Stuff Sack
Our stuff sacks are pretty dope, but current weight saving trends in ultralight circles eschews this once crucial item. So, opt out and save $ while also being very current.