Sea to Summit Ascent II Down Sleeping Bag

-9°C Comfort Limit (EN13537:2012), 550g of 750+ Fill Power ULTRA-DRY Down (US Method)
Weighs 1074g (Regular bag)
Code: SS191482
  • £329.99
  • (FREE Delivery on orders over £15)
  • RRP £369.99
+ In Stock Now | Usually dispatched within 24 hours

Sea to Summit's Ascent II Down Sleeping Bag is a super warm and versatile bag with its triple zip system allowing you to let heat out or keep it in as much as you want with the option of going full on quilt.

Sea to Summit says:

Light, warm, comfortable and most importantly, adaptable. The Ascent™ is our sleeping bag of choice for most adventures, most of the time. Offering the perfect backpacking balance of comfort vs weight, our Ascent™ Series sleeping bags have more space than traditional mummy bags, yet still provide the thermal efficiency you need when exploring above the tree-line.

The 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 provides freedom of movement for both arms, additional ventilation and means the top third of the bag can be folded down as a mini quilt. The full length, two-way left side zip and separate foot zip transforms the bag into a full quilt for when the mercury climbs higher than expected.

If it’s warmth you’re after, close all the zips, pull the cord locks tight to drag everything in, and relax in luxurious comfort. The generous allocation of high quality 750+ Loft down ensures great insulation, while the oversized draft tubes prevents your body heat escaping. The panelled footbox and 3-dimensional hood make sure you’re not compressing the down when you’re trying to stay warm. Vertical baffles over the chest section ensure the down insulation cannot migrate or shift to the outside of the bag during sleep, creating cold spots. A side block baffle construction maintains the 60/40 fill ratio, keeping more down on the top of the bag for maximum insulation.

Sea to Summit's Ascent II Down Sleeping Bag is light, super warm and adaptable bag thanks to its triple zip system. Depending on your needs the bag can be fully zipped up and and cinched in with the draw cord to maximise heat retention. With the full length zip with a an overlapping extra zip at the foot box the Ascent bag can be used as a quilt.

The third zip is on the right hand side which gives you an extra venting option or as its 2 way you can just allow your arm out to help you get a brew on without leaving the warmth of the bag. A generous 550g of responsibly sourced and dry treated 750 fill power provides the warmth. The tapered rectangular shape gives you more wriggle room than with a mummy bag and makes it a more effective quilt when fully unzipped. The large neck tube adds further warmth and comfort when you need to hunker down.

The Ultra Sil Compression bag allows you to mimimise the pack size of this excellent sleeping bag.

- Reviewed by Ultralight Outdoor Gear

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Help and advice: Choosing a sleeping bag advice
  EN 13537 rating for sleeping bags explained
  Sleeping bag shape and sizes advice
  Sleeping Bag features Page 1
  All about down filling in sleeping bags
  • Tapered rectangular shape for perfect balance of space and adaptable warmth
  • Super-light 20D Nylon shell and lining fabrics for minimal packed size and maximum breathability
  • RDS 750+ Loft ULTRA-DRY Down™ for superior insulating power
  • Vertical chest baffles prevent down migration and cold spots
  • Free-Flow half right side, full length two-way #5 YKK left side and separate foot zips for freedom of movement, increased ventilation and dual-use as a quilt
  • Oversized draft tube with anti-snag materials, prevents heat loss through zipper
  • Oversized neck draft tube with a dual adjustment system for even cinching and maximum warmth
  • Generously sized hood and dual cord adjustment for maximum warmth retention
  • Anatomically shaped footbox allows maximum down lofting, minimising heat loss from your feet
  • Large internal security pocket
  • Includes Ultra-Sil™ Compression Bag for compact storage
  • Zip Coupling: This bag can be zipped to the Sea to Summit Women’s Altitude, Journey and Venture sleeping bags

Temperature Rating

  • EN13537:2012 Comfort: -3°C / 27°F
  • EN13537:2012 Comfort Limit: -9°C / 15°F
  • EN13537:2012 Extreme: -28°C / -18°F

Regular Specs

  • Weight: 1074g (excludes storage bags)
  • Fill weight: 550g
  • Fits up to: 6 ft / 183 cm
  • Internal Width Shoulder: 155cm / 61 in
  • Internal Width Waist: 146cm / 57 in
  • Internal Width Feet: 122cm / 48 in


  • Insulation: ULTRA-DRY Down® 750+ Loft, RDS 90/10 Premium Duck Down
  • Shell: Lightweight 20D Nylon Shell
  • Lining: 100% Nylon
  • Zipper: Left-side #5 YKK zipper
  • Comes with: Ultra-Sil™ compression bag and storage cell
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