How to Choose Sleeping Bags for Backpacking
Sea to Summit Spark Sp II Sleeping Bag
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This ultralight 850-fill-power down sleeping bag balances size, weight and warmth, making the lightweight Sea to Summit Spark Sp II bag ideal for summer backpacking, cycle touring and mountaineering.
Shop similar productsKey Details
Fill
850-fill goose down
Compressed Volume
2.9 liters
Temperature Rating (F)
35 degrees (F)
- High-loft, premium 850-fill-power European goose down offers superb warmth with minimal weight; Ultra-Dry Downâ„¢ water-repellent treatment protects down from moisture
- Ultra-Dry Down is a water-repellent polymer treatment applied to the down; Ultra-Dry Down retains 60% more loft and absorbs 30% less moisture than untreated down
- With a European Norm (EN) lower-limit rating of 35°F, the Sea to Summit Spark Sp II will keep you warm on 3-season backpacking adventures
- Ultralight 10-denier nylon fabric with a durable water repellent treatment sheds moisture
- Soft 15-denier nylon fabric lines the Sea to Summit Spark Sp II Sleeping Bag for excellent comfort next to skin
- 1/3-length zipper saves weight over a full-length zipper
Temperature ratings are intended as a guideline to help you compare products, rather than a guarantee of warmth, since many different factors contribute to your comfort while you sleep. Backpacking bags are typically rated for temperature according to an independent testing protocol—currently International Organization for Standardization (ISO) 23537, though some older items followed European Norm (EN) 13537. Testing is based on a person wearing one base layer and a pair of socks, sleeping on an insulated surface with a minimum R-value of 5.38.
Each bag then gets 2 ratings: the Comfort rating is the lowest temperature at which the bag will keep the average "cold sleeper" comfortable, and the Lower Limit rating is the lowest temperature at which the bag will keep the average "warm sleeper" comfortable. Some brands determine their own temperature rating by aligning to the Comfort rating for women’s bags, to the Lower Limit rating for men’s bags, or somewhere in the middle for nongendered bags.
View all Sea to Summit Backpacking Sleeping BagsEach bag then gets 2 ratings: the Comfort rating is the lowest temperature at which the bag will keep the average "cold sleeper" comfortable, and the Lower Limit rating is the lowest temperature at which the bag will keep the average "warm sleeper" comfortable. Some brands determine their own temperature rating by aligning to the Comfort rating for women’s bags, to the Lower Limit rating for men’s bags, or somewhere in the middle for nongendered bags.
| Best Use | Backpacking Mountaineering |
|---|---|
| Tested Lower Limit | 35 degrees (F) - EN |
| Tested Comfort | 44 degrees (F) - EN |
| Temperature Rating (F) | 35 degrees (F) |
| Temperature Rating (C) | 2 degrees (C) |
| Shell | Ripstop nylon |
| Zipper Location | Left |
| Insulation Type | Down |
| Water-Resistant Down | Yes |
| Fill | 850-fill goose down |
| Lining | Nylon |
| Sleeping Bag Shape | Mummy |
| Stuff Sack Size | 5 x 10 inches |
| Stuff Sack Volume | 3.3 liters |
| Compressed Volume | 2.9 liters |
| Gender | Unisex |
Buying Advice
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Most Helpful Favorable Review
Excellent product. 100% satisfied
jpow10 years ago
I bought this bag mostly for summer backpacking. It is extremely lightweight and packs down to a minimal size (about the size of small football). That alone was what "sparked" my interest in this product. If you are a minimalist backpacker then this is probably the best bag out there for summer treks. I like to motorcycle camp as well so packing light and small is important.
I used this for the first time when I was yurt camping in the winter. Knowing that I'd be in a nice, warm yurt I packed it along because staying warm was not an issue. At night time we opened the top vent to the yurt to air it out. Throughout the night the fire in the stove died and the temperature dropped. I woke up at about 6:00 am and checked the thermometer. The temperature was 37 Fahrenheit. In the sleeping bag I was starting to feel a little cold but was still quite comfortable. This surpassed my expectation though, as the lower limit is 35 degrees and the comfort zone rating is 45 degrees. I'm a thin guy so I don't have much built-in insulation and I need a warm bag. I honestly don't know what the first reviewer is talking about because it is the exact opposite of what I experienced. I can't wait to use it this spring/summer!!!
jpow
Boise, ID, United States
48 people found this review helpful
Most Helpful Critical Review
horrible bag- run the other way!
walker1910 years ago
This bag says all the right things in the specs but does not follow through in performance. The zipper is only down about 2' which may help keep body heat in but it also makes getting in and out of it a huge pain. Especially in the night. Everything in the tent is upside down by the time you get back in it in the dark because you have to push it down to the bottom of the sleeping pad and shimmy in it. I used this bag at Caines Head/Seward Alaska in July (was around 50 in the mornings) and Colorado camping trip in August (very warm there) and I woke up shivering every night I used it on those two trips. Ive never woke up shivering in any sleeping bag before this one. It was upsetting because it does pack down into a very small package and is super lightweight which is really nice. But honestly it isnt worth the smaller size when your cold. And by the way, I was wearing fleece pants, fleece shirt and a lightweight down jacket and socks when I was in it freezing.... Really cant recommend this at all.
walker19
anchorage ak
10 people found this review helpful
Customer Images
jpow
Boise, ID, United States
Excellent product. 100% satisfied
10 years ago
I bought this bag mostly for summer backpacking. It is extremely lightweight and packs down to a minimal size (about the size of small football). That alone was what "sparked" my interest in this product. If you are a minimalist backpacker then this is probably the best bag out there for summer treks. I like to motorcycle camp as well so packing light and small is important. I used this for the first time when I was yurt camping in the winter. Knowing that I'd be in a nice, warm yurt I packed it along because staying warm was not an issue. At night time we opened the top vent to the yurt to air it out. Throughout the night the fire in the stove died and the temperature dropped. I woke up at about 6:00 am and checked the thermometer. The temperature was 37 Fahrenheit. In the sleeping bag I was starting to feel a little cold but was still quite comfortable. This surpassed my expectation though, as the lower limit is 35 degrees and the comfort zone rating is 45 degrees. I'm a thin guy so I don't have much built-in insulation and I need a warm bag. I honestly don't know what the first reviewer is talking about because it is the exact opposite of what I experienced. I can't wait to use it this spring/summer!!!
Yes , I recommend this product
James_m
Port Angeles, Wa
Best bag ever
7 years ago
The first time I used this was on one of the windiest and wettest nights I’ve ever spent outside, in a tent that I hadn’t seamsealed since last season, the wind and rain blew half the tent on me constantly throughout the night and I was worried about the bag since it’s down, I didn’t need to. At 1 or 2 in the morning I had to get up to fix the stakes and was very worried by the small puddle around my feet and the rain droplets covering my bag, I checked my bag and cleaned up the water but my bag was completely dry still, and I slept great! Later that year I would use it with a bivy sack that was better at keeping water in the keeping it out, again the bag proved itself and kept me amazingly dry and comfortable.
Yes , I recommend this product
traveling PT
Received free product
Northern CA
great lightweight 3-season option
8 years ago
I purchased this bag a few months ago in anticipation of summer trips sleeping on the coasts of California and Oregon as well as up in the mountains. This bag has not let me down in any aspect. I have slept in temperatures down to 37° at night and not had issues. (I am 6'7", 250#) I don't wear any clothes save boxers when I sleep and I am very warm and toasty when I wake in the morning. It is important to note that everybody's perception of what is truly cold will vary and therefore somebody who is simply cold in this bag must realize it might not be the right one for them. The short zipper is a little bit annoying when you have to get up at 2 AM to use the toilet, but the trade-off for the weight savings has really paid off. This is a great bag for somebody who does not mind a minor inconvenience of the zipper and appreciates a light bag that will do the job when used correctly.
Yes , I recommend this product
thedayhascome
Indianapolis, IN
High-Performing Super Lightweight Bag
8 years ago
I bought this bag after reviewing several other high performance, ultralight bags and quilts. The three factors that I was looking for were warmth at around 30-40° F, super light, and compressible. This bag delivers on all of those fronts. I have used this bag for several overnights reaching into 50° - 40°s and have been very warm. It has been used both in a hammock and on the ground paired with a Sea to Summit Ultralight Insulated pad. While slightly more difficult to get into while in a hammock due to the 1/3 zipper design, it is doable. Due to the mummy design, I would recommend this to those who can easily sleep on their backs. If you toss and turn a lot, then you may need a larger rectangle design bag. At only 16.4oz, this thing is crazy light and compresses down to the size of a small cantaloupe as seen in the photos. Comparing other 1lb bags and quilts, and comparing this bag to some cottage company down quilts, you also gain the warmth of the mummy style design and the bag wrapping around your head. You just can't beat the weight to warmth ratio. I have not had any issues with cold air in the sewn-through footbox, nor have I had any issues with the zipper from the previous reviewer. I would say if you are caring for your gear and not man-handling the zipper, you will be fine. Just carefully zip as you should be doing anyways and you'll have no problems. Highly recommend this bag, look forward to using it much more throughout the cooler Fall season.
Yes , I recommend this product
vince r
Houston, TX, United States
clothing the issue
10 years ago
Bag is fine. Previous poster needs to remove clothing when in a bag like this. Clothing accumulates moisture and will cause you to feel cold.
Yes , I recommend this product
mEp_
San Antonio, TX, United States
Best Three Season Bag
8 years ago
This bag will deliver on the promise of warmth. In summertime mountains of Colorado when the crisp night dipped into the high 30s I was comfortably warm wearing only a t-shirt and thin pants. The loft remained all around and on top, and with a simple pad I had no issues through the mountain nights. I can only possibly complain about the convenience of this bag. Any larger person may feel like they're being prepped into becoming a tamale as this bag doesn't offer much room for movement. It's width is very narrow so expect be uncomfortable if you have wide shoulders.....or a big stomach. The zipper is very short so I could see entering/exiting the bag becoming a hassle for some. None of these were issues for me, but I can completely see them being an issue for some. I entirely recommend trying out the bag before purchase with that in mind. Beyond those possible shortfalls I have yet to have an issue with the bag. It stuffs into an incredibly small size, it's nearly weightless for it's temperature class, and it is always cool to see the down through the bag's fabric. This is the best three season bag I have owned.
Yes , I recommend this product
MoabGirl22
Compresses very small = space saver
7 years ago
Needed a new summer bag and this one is perfect. Light weight, compresses small, but keeps you warm. 5'3" 115 lbs and this bag has plenty of room. I have no issues getting in or out with the smaller zippered opening.
Yes , I recommend this product
jscharg
Denver, CO, United States
light and compact
8 years ago
I bought this per the recommendation of an REI sales lady. The conversation went something like this: "I love my Marmot 0 degree synthetic bag, but I want an additional bag that is way more compact and lightweight, that takes up way less space in my pack". Her response: "I have the Sea To Summit Spark Sp II, and I love it. It definitely meets your criteria." I used it for the first time on a 10th Mountain Division hut trip last week with my wife and two young kids. I have yet to sleep outdoors with it, so the jury is still out regarding outdoor camping. Based on my hut trip experience, I love this bag. It packs down to the size of a Nalgene bottle. I am 5'9", 145 pounds, and I found the standard sized bag to be sufficient. I was comfortable sleeping in it --- not constricted at all. I lined the inside with the Sea To Summit Reactor Plus Thermolite, which has a nice comfortable material to it. I like that the bag is not very noisy when you move around in it. I had to wake up in the middle of the night to go to the bathroom, and it made very little noise as I got myself out of and then back into the bag. I definitely recommend this product.
Yes , I recommend this product
Coach Rev
Nebraska, United States
Zipper too short
8 years ago
As a tall guy, having a zipper only about a fourth of the length makes getting in and out of this bag near impossible. I'm swapping it out for another bag with full side zipper. For ultralight use, it's a great bag, and if extra warmth is needed, a thermal liner would work well.
No, I do not recommend this product
MaxS
Dissapointed
9 years ago
I bought this bag for a 5 day camping trip I recently went on. Zipper broke the second night and I froze the rest of the time because I couldn't close the bag. I didn't muscle it or anything; it just came apart. I sent the bag back to Sea to Summit and they repaired the zipper and sent it back. They offered no explanation. I don't trust it now as its got the same inadequate zipper that is better suited to be on a ladies undergarment. I expect more from a $350 piece of gear.
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