Ascent Down Sleeping Bag (-4°C, -10°C & -18°C) 2022Out of stock
BEST USE: Backpacking
PERFORMANCE: 2.5 Season
WEIGHT: 1lb 14.3oz | 860g
COMPRESSED VOLUME: 4.9 liters
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The Ascent down mummy sleeping bag redefines the meaning of versatile. Complex construction and high-quality down keep you warm when it's cold outside, while the triple-zipper Free-Flow Zip system ensures you stay cool and ventilated when the weather warms.
Shaped to allow a natural sleeping position for comfort, while light and compact enough to go anywhere.
Comes WithUltra-Sil compression bag and storage cell
InsulationUltra-Dry Down 750+ Loft
Shell FabricLightweight 20D Nylon Shell
Zip OptionsFree-Flow zipper system
|Ascent I (-4°C) Regular
|Ascent I (-4°C) Long
|Ascent II (-10°C) Regular
|Ascent II (-10°C) Long
|Ascent III (-18°C) Regular
|Ascent III (-18°C) Long
The second highest-lofting down used in any of Sea to Summit’s sleeping bags. 750+ Fill Power indicates that one ounce (30g) of down will re-expand to over 750 cubic inches after compression. Higher loft means that less down can be used to achieve the same temperature rating – important for performance sleeping bags. The loft and down quality/composition are independently tested by the International Down and Feather Laboratory (IDFL) – a copy of the certification is supplied with every Sea to Summit sleeping bag. The down is responsibly sourced and RDS certified and treated with the environmentally-friendly Ultra-Dry Down treatment.
100% of the down used in our sleeping bags and quilts is independently certified to the Responsible Down Standard (RDS). The RDS certifies down against animal welfare requirements and tracks it from the source to the final product. The purchase of RDS certified products demonstrates demand for better animal welfare practices in the down and feather supply chain. Sea to Summit is certified to the RDS. To learn more about RDS visit
Down and synthetic bags identified with our zip coupling symbol use a 65 inch #5 YKK full-length zip which allows a unisex left-handed and women's specific right-handed bag to pair together. Designed to pair side by side, each person sleeps in their own bag enabling each of you to take advantage of your bag's unique insulation zones, hood and footbox features - perfect for cozy adventures for two. Bags with full-length #5 YKK zips on both sides can also be coupled together with other pairing bags.
Our Free-Flow triple-zip design ensures your sleeping bag retains maximum warmth and efficiency when needed and multiple ventilation options when it's not. The half-zip on the right side of the bag (left side on women's bags) provides freedom of movement for both arms, additional ventilation and allows the top third of the bag to be folded down as a mini quilt when the mercury climbs higher than expected.
Frequently Asked questions
Warm enough for cold-weather use?
Yes. The high-lofting down, technical hood, oversized draft tubes, and draft collar make the Ascent -4°C and -10°C true 2.5 – 3 season bags. For colder weather, you might choose the Ascent -18°C and pair it with a greater than 3.5 R-Value sleeping mat like the Comfort Light Insulated.
Really cool in summer temperatures?
Yes. The Free-Flow Zip system means separate zippers on your left and right side and in the foot box. Open them for ventilation or to turn the Ascent into a comforter.
Able to be zipped to another sleeping bag?
The main side zipper can be zipped to the Sea to Summit Women’s Altitude, Journey and Venture sleeping bags. The Ascent Regular and Long bags have the same side zipper length.