Alpinist Center Zip Mummy - Four Season

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Due to move this product is unavailable until late 2022.

The Alpinist is Nunatak's center zip mummy bag.


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Due to move this product is unavailable until late 2022.


In our line-up for more than 20 years, the Alpinist is based on a design pioneered by Yvon Chouinard in the early seventies. The original is allegedly still used by Chouinard, as mentioned in the 2017 Patagonia catalog.

The unique center zip location is perfect for side sleepers and back sleepers alike. It also gives you full use of both arms while still having head and back snug in the sleeping bag, a must when performing sitting camp tasks in less than ideal conditions.

When side sleeping the zipper typically ends up slightly in front, down from the shoulder a bit. Whether it is open for venting or snugged up, this is an ideal location. From here the zipper is conveniently controlled without contortions, and the dreaded back side cold spot from traditional zipper placement on the side hem, is completely eliminated. In fact, side sleeping is almost where the center zip placement is at its best.

The Alpinist is built with a differential cut, a feature that greatly increases the efficiency of a given fill volume; and the zipper is backed by a double set of draft tubes. Internal draft collar is standard.

Take note that the Alpinist performs best close to its comfort rating, as venting the lower portion is difficult on warmer nights. For general backpacking the versatility of the zippered 3D Quilt is superior.


Two levels of insulation. Conservatively defined as 15°F or 5°F. The loft is a minimum of 2.75" and 3.25".  Fill volumes for either level are detailed in the charts below, and offer further insight into whether these quilts will meet your needs. 

Advanced baffle layout. Together with our carefully calculated fill volumes, the tapered and individually optimized baffles help to eliminate migrating down and cold spots. Along with loft, these are crucial design components for a cold weather quilt.

Internal shoulder level draft collar. Down filled on 15°F and 5°F versions - unfilled on 35°F and 25°F bags.

Differential cut. The outside of the bag is built with a proportionally larger girth and length. This keeps the insulation fully lofted even when attacked by a restless sleeper.

Enhanced moisture protection in areas of exposure. Optional waterproof/breathable fabrics protect the upper bag where moist exhalations can wet out the insulation; as well as the foot section, an area often rubbing with damp shelter walls. This performance fabric adds little additional weight to a finished Alpinist.

Goose down. We use only high quality 900 fill power goose down, in plain untreated or Hyper-Dry to resist loft-killing moisture. Our batches are certified ethically sourced/harvested and can be tracked upon request.

Optional lining of extra durable fabric in the fully enclosed footbox. This area typically sees the most wear, whether from calloused feet or the storing and drying of footwear. Substituting the standard liner for a 20D material gives this area an edge in long term durability. Expect a minor weight increase.

Dual draft tubes along the zipper

Adjustable cord around the snug hood opening.

Two way #5 zipper.

NOTE: These highly specialized bags have a narrow comfort range due to the center zip efficiency and lack of venting options for the foot end:

15°F : 10°F to 20°F

5°F : 0°F to 10°F

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Alpinist Center Zip Mummy - Four Season

Alpinist Center Zip Mummy - Four Season

Due to move this product is unavailable until late 2022.

The Alpinist is Nunatak's center zip mummy bag.


Product Options
15°F / -10°C
5°F / -15°C
Inside Length
Choose a length closely matching your height. Size up if needed.
Shoulder Width
54" inside circumference. Small frames, skinny people
60" inside circumference. Fits most.
66" inside circumference. Very roomy.
Footbox Size
Custom sizes are available for the fully enclosed mummy style foot. Choose the bigger 44" only if you have large feet (11>) or wish to store and dry items inside.
40" circumference foot end
44" circumference foot end
Shell Material

Two options: Ultralight 10d for the lightest, most breathable and best lofting performance. 15d for more durability and tear resistance with only a small weight penalty.

Waterproof/Breathable Shell Options

This selection substitutes a 7d waterproof/breathable shell fabric to the lower third, plus the head opening. The large torso middle section remain with the classic 10d/15d breathable fabric.

No Thanks!
Black Robic Weatherproof 7d - Applied Only to Lower Third and Top Draft Collar
Liner Material
Breathable 10D Taffeta, Black.
Inside Footbox Liner upgrade

Adding the burlier 20D liner fabric option to the foot area gives this high wear area a little more durability for the long term. Also useful if storing and drying items inside the quilt.

No Thanks!
Yes, please include 20d durable foot liner material
Down Type

We use 900 fill power goose down, certified responsibly sourced.

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 untreated down.

Differential Cut
The standard differentially cut design creates a bigger shell compared to the liner. This allows the insulation to achieve full loft and helps eliminate cold spots.
Yes. Please!
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. The amount depends on the product, the size and the rating.
No Thanks
Overfill in foot section
Overfill in torso section
Overfill evenly throughout
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.
No stuff sack
Yes, please include a stuff sack
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