Not many campers need a bag this warm and waterproof, but if you’re one—you know who you are—the Altitude delivers the whole package. “I felt like I was hibernating each night,” says a tester who used it for a month straight on a late fall hunting/backpacking trip through Montana, Wyoming, and Colorado. “I typically sleep cold, and this bag never failed me in temps near zero,” he says. “It maintained its loft throughout the entire trip.” The Altitude’s 800-fill down is protected from the elements by a waterproof/breathable ShelterTX shell and full-length, rubberized, splashproof (not totally watertight) zipper.
Our tester credits the all-conditions warmth with saving him from hypothermia on a single-digit bivy gone bad—real bad, with rain, hail, and sleet. Details are dialed for heat: Lofty dual draft tubes prevent even the hint of cold air from sneaking in, and a built-in fleece facemask is welcome on frigid nights (and folds away when not needed). “And the parkalike hood is stellar,” says a Montana tester. “It hugs my shoulders, neck, and noggin, leaving no dead air space.”
Bonus: Dry wet clothes in a mesh pocket inside the chest area. Downsides: There’s the price, of course, and even with the included compression sack, it packs down to the size of a standard bear canister. $680; 3 lbs. 10 oz.; -10°F
Mammut's down bag for warmer climates. Completely re-designed for Summer 2009, the Altitude Spring features advanced baffling construction to eliminate cold spots, a Hot Head Hood for maximum head protection from the cold, and a differential cut to save weight, improve loft and increase insulation capacity.
Construction: Advanced Baffling
Fill: Goose Down-800
Fill Weight: 260g / 240g
US Temp. Rating: +25F