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A feature-rich expedition bag built for sustained comfort in extreme cold
Thermarest says:
The lightest, most feature-rich down sleeping bag for high-performance in the extreme cold.
Designed in conjunction with renowned polar explorer Eric Larsen, the Polar Ranger -20F/-30C down sleeping bag is built for the coldest places on earth. Previously a recipient of Backpacker Magazine’s Editor’s Choice Award, the lightest and most feature-rich bag in its class just got better. It utilizes cutting edge box-baffled construction and is filled with highly compressible, PFC-free 800-fill Nikwax Hydrophobic Down™. This advanced down maintains its loft and warmth longer, even in the challenging conditions of extended expedition use in the arctic cold. It absorbs 90% less water and dries 3x faster than untreated down—a big plus on long trips where periodic drying is required. The ultralight shell and soft liner are made from planet-friendly GRS-certified 100% recycled nylon. A unique snorkel hood with a magnetic closure helps seal in warmth while routing exhaled moisture away from the bag to preserve loft. Drafts are kept at bay by extensive, overstuffed draft tubes and a pair of side vents allow for custom ventilation while freeing your arms while still in the bag. Other features include an insulated Toe-asis™ foot-warming pocket, SynergyLink™ Connectors to link bag and sleeping pad, an interior stash pocket, external loops for attaching a quilt or blanket for more warmth, and an anti-snag YKK® zipper.
Our Verdict
The Polar Ranger is built for sustained cold and expedition use. There is a clear focus on maintaining warmth and comfort over long nights in harsh conditions. At 1538g, it sits firmly in the expedition category, trading low weight for consistent performance in very cold conditions.
The fit is noticeably roomier with extra layers, and it works well for those like me who toss and turn overnight. The snorkel-style opening uses synthetic insulation instead of down, which helps manage moisture and reduce internal dampness, a key advantage in cold environments. Arm ports and side vents add practical flexibility, making it easier to adjust layers or handle small tasks without fully opening the bag.
The 800-fill hydrophobic down maintains high loft in cold, damp air, while the recycled shell fabric feels light yet robust.
Overall, this is a well-considered design for harsh conditions, where warmth and usability take priority over pack weight.
- Reviewed by Ultralight Outdoor Gear
Features
- Recycled Shell & Liner: GRS-certified 100% recycled fabrics are eco-friendly while being lightweight, soft and durable; anti-snag YKK zipper ensures easy entries and exits and prevents tears.
- 800-Fill Nikwax Hydrophobic Down™: PFC-free and absorbs 90% less water and dries 3x faster than untreated down.
- Responsible Down Standard Certified: Certification that ensures the waterfowl in the down supply chain are treated humanely.
- Snorkel Hood: Designed to allow for easy breathing and to ventilate exhaled moisture to preserve loft; magnetic closure keeps cross-drafts at bay and eases entry/exit.
- Side Vents: Allow for external arm use and customizable temperature control; overlapping draft tubes prevent cold spots when closed.
- SynergyLink™ Connectors: Removeable ultralight straps create a secure bag-to-sleeping pad connection that optimizes the comfort and thermal efficiency of your entire sleep system. SynergyLink Connectors function best with regular sized sleeping pads that are 3 inches thick or less when inflated.
- Additional Features: Toe-asis™ Foot Warmer Pocket, cinchable draft collar, YKK® anti-snag zipper, interior stash pocket, overstuffed draft tubes, external quilt loops, draft collar.
Specifications
Regular
- Weighs: 1538g
- Width: 32in/81.2cm
- Length: 81in/206cm
- Height: 6.5in/16.5cm
- Fits: 72in/183cm
- Girth Shoulder: 64in/163cm
- Girth Hip: 59in/150cm
- Girth Foot box: 46in/117cm
- Packed Dimensions: 8.5 x 10in/22 x 25cm
- EN Comfort: -20°C/-4°F
- EN Limit: -30°C/-20°F
- Fill weight: 2lbs 2oz/970g
Long
- Weighs: 1613g
- Width: 34in/86cm
- Length: 81in/218.5cm
- Height: 6.5in/16.5cm
- Fits: 78in/198cm
- Girth Shoulder: 68in/173cm
- Girth Hip: 60in/152cm
- Girth Foot box: 51in/130cm
- Packed Dimensions: 8.5 x 10in/22 x 25cm
- EN Comfort: -20°C/-4°F
- EN Limit: -30°C/-20°F
- Fill weight: 2lbs 6oz/1007g
Material & Construction
- Shell fabric: 100% Recycled Nylon RipStop w/ DWR
- Lining fabric: 100% Recycled Nylon RipStop
- Fill material: 800 Fill Goose Nikwax Hydrophobic Down RDS
