Sea to Summit Ascent 1 Sleeping Bag
The Sea to Summit Ascent 1 is a versatile and lightweight sleeping bag that can be used like a quilt in warm weather, opened at the feet and sides for ventilation on a cool night, and fully zipped with a mummy hood and shoulder baffles when the temperature drops into the 30s and below.
Ascent 1 Specs
MSRP: $399 (on sale for $239.40)
Temperature Rating: 35F comfort, 25F lower limit
Insulation: Ultra-Dry 750+ loft down
Size: Regular
Bag Weight: 1 pound, 14 ounces
Fill Weight: 11.6 ounces
Shell Fabric: 20D nylon
About the Ascent
Versatility is the Ascent’s strength: compatible Sea to Summit women’s bags can be zipped to the Ascent to form one bag; a zipper in the footbox can be opened for ventilation; a half zip allows the top of the bag to be folded down like a quilt; and the main zipper along with the footbox zipper can be opened to let the bag be more like a blanket. And the baffles lining all the zippers ensure that cold air doesn’t get in when the zippers are closed.
Ascent Features
Materials: The outer shell is made from lightweight 20D nylon, a durable but not heavy fabric weight.
Insulation: Responsible Down Standard (RDS) certified 750+ loft duck down with Sea to Summit’s Ultra-Dry down treatment that protects the down from external moisture and internal condensation. Sea to Summit also says Ultra-Dry down dries faster than untreated down.
Temperature Rating: I was comfortable at 37F, just above the comfort rating of 35F, while wearing my usual night clothes: lightweight long-sleeve shirt, long bottoms, and socks. At 29F, the lowest temperature I slept in, I added a midweight top and was comfortably warm with the hood and shoulder baffles drawn tight. The lowest rated temperature for the bag is 25F, and I feel as though I would have been on the edge of comfortable warmth at that temperature.
Weight: 1 pound, 14 ounces for a regular size. Not ultralight, but still a lightweight bag.
Bag Construction: The vertical baffles over the chest are meant to prevent down from shifting while rolling over in your sleep, while the lower bag from about the waist down and all of the bag’s back have the traditional horizontal baffles. The footbox is squarish for more foot room.
Baffles: Generous baffles line all the zippers, the shoulders, and the hood.
Footbox: The footbox zipper lets you open the bag at the bottom for ventilation on warm nights, but when the temperature drops and the zipper is closed a baffle keeps cold air from getting in.
Mummy Hood: Although the hood is on the small side, my inflatable Sea to Summit Aeros Ultralight Pillow fits inside.
Zippers: Mastering what Sea to Summit calls its Free-Flow triple-zip on the Ascent takes a few minutes, so it’s a good idea to practice before heading into the backcountry.
- Main Zipper: This one’s easy enough. The left side zipper is the standard two-way sleeping bag zipper, with top and bottom sliders. I can zip the sleeping bag closed around my head and open the bottom slider to provide ventilation.
- Half Zipper: On the right side of the bag, opposite the full zipper. This zipper slides down to make the sleeping bag more like a quilt or blanket.
- Footbox Zipper: This opens the sleeping bag at the bottom for additional ventilation. It’s even possible to slide your feet through the footbox opening and put on shoes, keeping the bag around you on cold mornings.
No-Snag Zippers: A wide strip of stiff fabric alongside the zippers keeps them from snagging on the baffles, ensuring the zipper didn’t snag during my nighttime visits to the privy.
Drawstrings: I like the separate drawstrings for the hood and shoulders, both of which have baffles to keep out air. These let me tighten the bag at my shoulders in moderate temperatures to keep cool air from getting into the body of the bag while letting the hood fit loosely around my head. The shoulder baffle also lets me use the bag more as a quilt, without using the hood. Or I can use the hood in cold weather and tighten both drawstrings to keep out cold air.
Inner Pocket: Big enough to hold a small headlamp, but I couldn’t fit my iPhone11 in it. And the 11 is small compared with the later iPhone models.
You’ll Stand Out: The neon green color of the Ascent means you’ll be able to pick out your bag in a packed shelter.
Fit: I’m 5 feet, 10 inches, 160ish pounds, and the regular size bag is a good fit for me.
Accessories: Lightweight Ultra-Sil compression bag for the trail and large storage bag for home.
Room for Two: The Ascent’s #5 YKK zipper allows the bag to be paired with the women’s Sea to Summit Altitude, Journey and Venture sleeping bags.
Bags for Different Temperatures: The Ascent comes in a 25F EN (European Norm) rated bag, which is what I tested, and in 0F and 15F bags. All have 750 fill down, and the bags listed below are regular size.
- Ascent 3: 0F, 2 pounds, 14 ounces, $499.
- Ascent 2: 15F, 2 pounds, 6 ounces, $449.
- Ascent 1: 25F, 1 pound, 14 ounces, $399.
Manufactured: In China
Ascent Pros
Zippers, Zippers, Zippers: The three zippers make the Ascent 1 a versatile bag for three-season camping.
Weight: The Ascent isn’t ultralight, but at 1 pound, 14 ounces it’s a bag that packs small and carries light.
Warmth: The Ascent lives up to its rating of 25F for the lowest temperature limit.
No-Snag Zippers: The wide, firm strip of fabric alongside the zippers makes the Ascent easy to get in and out of without fumbling with a stuck zipper.
Ascent Cons
Too Many Zippers?: The array of zippers may not be for hikers who just want to deal with one zipper.
Overall Value
The Ascent 1 has a lot going for it with the bag’s versatility, light weight, and warmth. The $399 price is slightly less than comparable sleeping bags, and Sea to Summit’s holiday sale makes the Ascent’s price more attractive.
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This product was donated for purpose of review.
