Wednesday, October 4, 2023

Sea-to-Summit Spark 1 Sleeping Bag Overview (40-degree)

The Sea-to-Summit Spark 1 (40-degree) is an ultralight down sleeping bag that weighs 12 ounces (340g) and is insulated with 850-fill energy waterproof down. The Spark 1 has a sewn-thru development and a one-third-length zipper to avoid wasting weight. When stuffed the Spark 1 packs all the way down to the dimensions of a baseball (1.5L) making it good for journeys the place pack house is at a premium. Its unbelievably low weight will attraction to anybody attempting to shave ounces or grams from their pack weight.

RELATED: 10 Greatest Down Sleeping Luggage for Backpacking

Specs at a Look

  • Gender: Unisex
  • Weight: 12 oz (Measurement common, Size 72″)
  • Precise Weight: 12.5 oz on the SectionHiker digital scale
  • Fill Weight: 6.3 oz
  • Sizes: common,
  • Sort: Mummy
  • Packed Measurement: 1.5L
  • EN Restrict Temperature Score: 40F (5C)
  • EN Consolation Temperature Score: 48F (8.9C)
  • Building: Sewn-thru
  • Girth/Hips/Footbox (dimension common): 59″, 51″, 35″
  • Insulation: 850 Fill Goose Waterproof Down RDS
  • Zipper: One-third zipper, 2-way
  • Zipper Facet: Left
  • Draft Tube: No
  • Shell/Liner Cloth: 10D Nylon RipStop with DWR / 7D Nylon RipStop
  • Stuff Sack: Compression sack included and a material storage bag
  • Go to Sea-to-Summit for full Specs

Ultralight Design Options

At simply 12 oz, how did Sea-to-Summit make this sleeping bag so light-weight?

First off, the sleeping bag is sort of tapered and is designed to fit your needs with out plenty of further inner house. I can match into its 59″ shoulder girth (dimension common) however there isn’t a complete lot of additional room for me. The footbox is relatively spacious, nonetheless, and my ft can simply splay aside comfortably.

Subsequent, Sea-to-Summit makes use of very light-weight materials on the Spark 1 together with a silky 7D nylon liner and an ultralight 10D exterior nylon shell. Each of those materials are PFC-free.

Lastly, the Spark 1’s zipper is just one/3 size offering further weight financial savings. As a result of it’s a warm-weather bag, it doesn’t have a zipper draft tube or a chest draft tube, which saves further weight. The zipper is two-way and has a snap on the prime so you may unzip and vent the torso should you get too heat. The snap additionally takes any pressure off the zipper, including to its longevity. Nevertheless, the zipper doesn’t have any anti-sag taping alongside its size, once more to avoid wasting weight, so you should watch out to not have it jam or doubtlessly tear the liner and shell cloth when opening or closing it.

The baffles are oriented vertically over the chest and horizontally over the legs.
The baffles are oriented vertically over the chest and horizontally over the legs.


The Spark 1 is insulated with 850 fill energy Nikwax “waterproof” goose down which is premium stuff when it comes to warmth-to-weight ratio. Larger fill energy down like this supplies extra heat by weight than decrease fill energy down and is used to avoid wasting weight. The waterproofing makes the down dry sooner if it will get damp or moist

The down insulation is oriented in vertical baffles over the hips and chest and in horizontal baffles over the legs and ft to assist stop down shift and maintain the down the place you need it. The baffle development is sewn-thru, relatively than being box-baffled to avoid wasting weight and maintain prices decrease. In sewn-thru development, the highest and backside cloth shells are sewn collectively to create tubes to carry the down in. Whereas this prevents downshift, it will possibly create chilly spots on the seams.

The Spark 1 has a 1/3 length zipper to save weight.
The Spark 1 has a 1/3 size zipper to avoid wasting weight.

Whereas the Spark 1 is rated for 40 levels, I’ve discovered it sleeps a bit of chilly at 50 levels, even when used with an acceptable sleeping pad and lengthy underwear. It’s nonetheless a viable possibility for hotter climate use, however I counsel you shakedown its consolation score earlier than relying on it near its consolation restrict.

The hood is flat and shallow, making it easy to sleep on your side, while still providing some coverage.
The hood is flat and shallow, making it straightforward to sleep in your facet, whereas nonetheless offering some protection.

Mummy Hood

The Spark 1’s mummy hood is fairly normal with a right-side elastic twine that allows you to cinch the hood closed. It doesn’t have house for a pillow, however it’s broad sufficient that you could comfortably roll over onto your facet whereas carrying it. The snap on the prime of the facet zipper helps seal the hood on the left facet and preserve its form even when the facet zipper isn’t absolutely closed. The hood can be fairly unobtrusive should you determine you wish to unzip up the sleeping bag and use it extra like a quilt.


The Sea-to-Summit Spark 1 (40) is an ultralight sleeping bag that weighs 12 ounces and is optimized for backpacking journeys the place house and weight are at a premium. It’s by far one of many lightest sleeping baggage or backpacking quilts out there right this moment.  For instance, a customized Enlightened Gear Revelation Quilt with comparable specs (fill energy, cloth weight) weighs 3 ounces extra. The benefit of utilizing a sleeping bag just like the Spark 1 over utilizing a backpacking quilt, in addition to the plain low weight and packability, is that you just’ll have a draft-free expertise with no need a bivy sack as a result of it’s utterly enclosed. In the event you want a sleeping bag over a quilt and wish an ultralight sleeping bag, the Spark 1 is a viable possibility price contemplating.

Disclosure: Sea-to-Summit donated a sleeping bag for assessment.

Examine 1 Costs

Final up to date: 2023-07-20 21:26:30

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