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Hands-on Gear Review

Sea To Summit Spark Sp II Review

Top Pick Award

Backpacking Sleeping Bag

  • Currently 4.0/5
Overall avg rating 4.0 of 5 based on 1 review. Most recent review: May 7, 2015
Price:   Varies from $359 - $379 | Compare prices at 3 resellers
Pros:  Super light, Highly compressible, Available from major online retailers
Cons:  Patchy cold spots, Not versatile
Best Uses:  Light and fast backpacking and mountaineering
User Rating:       (0.0 of 5) based on 0 reviews
Manufacturer:   Sea to Summit
Review by: Mike Phillips ⋅ Review Editor, OutdoorGearLab ⋅ May 7, 2015  
Our testers loved the Sea to Summit Spark Sp II sleeping bag when they wanted to save weight and space in their packs. It was awarded a Top Pick Award for light and fast backpacking and climbing trips. We found it to be an appropriate summer bag for middle elevation mountain terrain. We didn't think twice about carrying it for trips where we wanted to move fast and carry less weight. For a specialty sleeping bag, the price tag is fair, but don't count on this bag doing it all. The window of time for which it will be comfortable is limited. If you're going to spend more time carrying your sleeping bag than sleeping in it, consider a super light bag like this one. This bag is available from major online retailers, unlike the ultra-light sleeping bags featured in our Ultralight Sleeping Bag Review. For more well-rounded three-season sleeping bags, take a look at our complete Backpacking Sleeping Bag Review for better options.

RELATED: Our complete review of backpacking sleeping bags

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OutdoorGearLab Editors' Hands-on Review

New Review Coming: Fall 2015
Get psyched! Our reviewers are currently hard at work testing the latest version of the Sea to Summit Spark SP II! Check back this fall for a new review!

The Sea to Summit Spark Sp II is a surprisingly warm 1 pound sleeping bag. It's a great choice for backpackers and climbers looking to save weight and pack space for specific mountain objectives.

Performance Comparison

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The Spark SpII in the lightweight Black Diamond Betalight shelter on a trans-Sierra backpacking trip.
Credit: Mike Phillips


The Spark Sp II was much warmer than we expected it to be. It is shockingly light for a traditional mummy style sleeping bag. It feels like a cloud in your hands, and the white color makes that feeling even more convincing. You can literally see through the nearly translucent exterior fabric, and it is obvious that the down is of high quality as you feel the bag and look at the healthy down clusters inside. By looking through the exterior, you can also see why it sometimes feels like it has patchy cold spots. Down needs to be shifted around inside the baffles to maximize the distribution of the insulation. There is proportionally more down near the core of the body, just where you need it most to stay the warmest.


The Sea to Summit Spark Sp II weighs an incredible 18 oz. in a size long. It accomplishes this by featuring a slim fit, lightweight fabrics inside and out, a ⅓ length zipper, and 850+ fill down. There really isn't anything else to this bag. It is overall very simple in design, and weight and space are the primary considerations for anything that is part of this bag. The only bags featured in our Backpacking Sleeping Bag Review that compare weight-wise are the Mountain Hardwear Mountain Speed 32 and the Western Mountaineering Highlite. You can also explore our Ultralight Sleeping Bag Review for non-traditional sleeping bags that are more in the league weight-wise with the Spark.


Soft materials and soft, high loft down make the Spark a reasonably comfortable bag. It features a slim fit that allows little room for thrashing about inside the bag. However, it fits close enough that it is easy to move with the sleeping bag.

A note on fit…The size Long in the Spark Sp II fit 6'0" testers very well.

Packed Size

Sea to Summit provides a great stuff sack/compression sack with this bag. An especially small bag, it is important to be able to get the sleeping bag any smaller. All packed up, it is smaller than a football, making it really easy to squeeze into the corner of a very small pack.


The standout features of this bag are the high quality materials from which it is constructed. The shell of the bag is made from 10 denier Pertex Quantum fabric for minimal weight and bulk. 850+ fill down is the insulation of choice for lightweight sleeping bags like the Spark. Appropriate attention was paid to minimizing extra features so as to keep the weight down. Extras on this bag mean that things were taken away. The ⅓ length zipper, the slim cut, and the small diameter drawcord at the collar are all examples of this bag's minimalism.


Sleeping bags like the Spark Sp II are less versatile than general backpacking sleeping bags. Their minimalist design will not stand up to prolonged exposure in tough conditions.

Best Application

The Spark is best suited for specific mountain objectives where weight and space in your pack matters most. If going fast and light is most important to you, this bag excels as a small, light summer option.


Other approx. one pound sleeping bags like the Western Mountaineering Summerlite and the Western Mountaineering Highlite are comparable in price to this Sea to Summit option. The other contender for the lightest traditional mummy style sleeping bag in our review is the Mountain Hardwear Mtn Speed 32, which costs 100 dollars more. We consider all of these bags to be specialty sleeping bags that have a unique purpose in your backcountry gear quiver. If you are committed to lightening your pack so that you can take mountain trips to the next level, consider buying a lightweight bag like the Spark. If you are looking for a sleeping bag for versatility, look elsewhere.


The Sea to Summit Spark SpII is a super light, smartly featured, minimalist sleeping bag. It should be used for light and fast missions in the mountains where every ounce and every cubic inch matters. Well insulated for a lightweight, summer sleeping bag, the Spark is right at home in mid-elevation terrain. We recommend this bag for users who already have a three-season sleeping bag that is their all-purpose workhorse and need an ultra-light bag for specific mountain trips.

Other Versions

Spark SP I
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  • 46*F Version of the Spark lineup
  • 12.3oz
  • $300

Spark SP III
  • 25*F Version
  • 1lbs 6oz
  • $460

Mike Phillips

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OutdoorGearLab Member Reviews

Most recent review: May 7, 2015
Summary of All Ratings

OutdoorGearLab Editors' Rating:   
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Average Customer Rating:     (0.0)
Rating Distribution
1 Total Ratings
5 star: 0%  (0)
4 star: 100%  (1)
3 star: 0%  (0)
2 star: 0%  (0)
1 star: 0%  (0)

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Sea to Summit Spark II
Credit: Sea to Summit
Where's the Best Price?
Seller Price
Backcountry $358.95
MooseJaw $358.95
REI $379.00
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