Ascent -9C Down Sleeping Bag

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UOG TOP PICK—The Sea to Summit Ascent -9C is a premium down sleeping bag for cold-weather adventures. It provides warmth even in freezing temperatures. The bag is lightweight and features a relaxed mummy shape for comfort. The free-flow zipper system allows for venting and airflow control. It’s one of our top picks for cold weather.

Sea to Summit says: 

The Ascent Sleeping Bag is the most versatile in our sleep range and is suited to a multitude of climates, conditions, and adventures. From long distance hiking to weekend getaways, the ultra lightweight 750+ FILL Power offers added warmth in cooler climates while the Free Flow Zip System allows for added air flow and ventilation in warmer climates. Putting comfort and adaptability at the forefront, the Ascent Sleeping Bag is a premium option for  versatile adventures.

Our Verdict

The Sea to Summit Ascent -9C is a premium down sleeping bag designed for cold-weather adventures and winter camping. With an impressive EN comfort rating of -8°C (18°F), it provides toasty warmth even when overnight lows dip well below freezing.

Filling the Ascent, is premium 750+ fill power responsibly sourced duck down that lofts incredibly well for maximum insulation. The down’s ultra-dry treatment also helps it maintain performance if the bag gets damp from condensation or light precipitation.

Despite its warmth, the Ascent still manages to weigh just 1025g for the regular size, thanks to smart design, such as vertical chest baffles that minimize down migration. The relaxed mummy shape provides freedom to move without feeling constricted.

When overnight temperatures rise, the free-flow zipper system comes into play. You can open the full-side zipper for venting or use the half zipper and foot box zip to finely control airflow and prevent overheating.

Other valuable features include a waterproof, breathable shell over the hood/foot box, adjustable drawcord hood, draft tubes, and hang loops for drying. The Ascent packs down remarkably small for a -8°C bag.

– Reviewed by Ultralight Outdoor Gear

Features

• Duck Down with Ultra Dry Down treatment for improved water  resistance in damp conditions.
• The Free Flow Zip System offers temperature regulation and multiple sleeping bag configurations for added freedom in the outdoors
• With a spacious design, adjustment cord and room to fit a regular Sea to Summit pillow, the Technical Regular Hood offers comfort and flexibility for car camping and shorter adventures.
• Storage bag and compression bacg included

Specifications

Temperature Rating

• EN13537:2012 Comfort: -2°C | 29°F
• EN13537:2012 Comfort Limit: -8°C | 18°F

Regular Specs

• Weight: 1025g (excludes storage bags)
  
• Fill weight: 540g
  
• Fits up to: 6 ft / 185cm
• Internal Width Shoulder: 158cm
• Internal Width Waist: 146cm
• Internal Width Feet: 119cm
• Compressd Size: 13L

Long Specs

• Weight: 1166g (excludes storage bags)
  
• Fill weight: 617g
  
• Fits up to: 6 ft 6 in / 198 cm
• Internal Width Shoulder: 168cm
• Internal Width Waist: 156cm
• Internal Width Feet: 129cm
• Compressd Size: 13L

Fit

• Relaxed Mummy Fit: A more relaxed yet tapered mummy fit with high thermal performance.

Materials & Construction

• Insulation: 750+ FILL Power, RDS- certified, Duck Down with Ultra Dry Down treatment for improved water resistance in damp conditions.
• Fabric: Recycled 20-Denier Nylon shell and lining. 10-Denier Nylon waterproof-breathable hood and footbox.
• Zipper: Free Flow Zip System: Primary zip – full length #5 with zip-plow and two sliders.
  Secondary zip – 1/2 length #5 with zip-plow and two sliders.
  Footbox zip – #5 with two sliders.
• Baffle Construction: Vertical chest baffles, horizontal baffles lower half and base, box wall baffle construction throughout.
• Collar: Fitted front draft collar: scalloped over the neck and oversized at the shoulders.
• Hood: Generous fitted hood with two soft touch adjustments. Fits a Sea to Summit regular pillow.
• Draft Tube: Single, synthetic-filled, draft  tube along the top of all zippers.
• Intergration: Pairs with Women’s Sea to Summit bags, and STS quilts.

Help & advice:

• The Ultimate Guide to Lightweight Sleeping Bags
• Time-Saver Guide to Choosing a Sleeping Bag
• Sea to Summit Sleeping Bag & Quilt Guide
• About Sea to Summit
• The EN13537 Standard
• All About Down