Sea to Summit Spark SPI Sleeping Bag (Regular)
Incredibly lightweight and compressible, the Sea to Summit Spark SpI is ideal for ultra-lightweight warm-weather backpacking or thru-hiking. It weighs right around a pound, features weather-resistant treated down insulation, and has a temperature rating of 40 Degrees F. Renowned for their efficiency in retaining heat and compressible properties, the feathers and fibers of down have an incredibly soft, comfortable feel and, despite advances in synthetic materials, continue to provide the best warmth-to-weight ratio of any insulation available. The one inherent weakness of down insulation is that it loses much of its ability to maintain warmth when it gets wet, but the bag’s premium 850+ fill Ultra-Dry Down performs differently. Ensuring consistent thermal performance, a hydrophobic treatment enables the insulation to stay dry longer and dry faster if it should become wet than traditional down insulation. The bag uses lightweight 10 denier nylon on the exterior shell fabric and a 7 denier nylon interior lining. The bag uses sewn-though construction to save weight and keep insulation from migrating and creating cold spots. An insulated hood bolsters warmth. The Sea to Summit Spark SpI sleeping bag is available in your choice of Regular (fits up to 6’ 0”) and Long (fits up to 6’ 4”) size options.
Incredibly lightweight and compressible, the Sea to Summit Spark SpI is ideal for ultra-lightweight warm-weather backpacking or thru-hiking. It weighs right around a pound, features weather-resistant treated down insulation, and has a temperature rating of 40 Degrees F. Renowned for their efficiency in retaining heat and compressible properties, the feathers and fibers of down have an incredibly soft, comfortable feel and, despite advances in synthetic materials, continue to provide the best warmth-to-weight ratio of any insulation available. The one inherent weakness of down insulation is that it loses much of its ability to maintain warmth when it gets wet, but the bag’s premium 850+ fill Ultra-Dry Down performs differently. Ensuring consistent thermal performance, a hydrophobic treatment enables the insulation to stay dry longer and dry faster if it should become wet than traditional down insulation. The bag uses lightweight 10 denier nylon on the exterior shell fabric and a 7 denier nylon interior lining. The bag uses sewn-though construction to save weight and keep insulation from migrating and creating cold spots. An insulated hood bolsters warmth. The Sea to Summit Spark SpI sleeping bag is available in your choice of Regular (fits up to 6’ 0”) and Long (fits up to 6’ 4”) size options.
Incredibly lightweight and compressible, the Sea to Summit Spark SpI is ideal for ultra-lightweight warm-weather backpacking or thru-hiking. It weighs right around a pound, features weather-resistant treated down insulation, and has a temperature rating of 40 Degrees F. Renowned for their efficiency in retaining heat and compressible properties, the feathers and fibers of down have an incredibly soft, comfortable feel and, despite advances in synthetic materials, continue to provide the best warmth-to-weight ratio of any insulation available. The one inherent weakness of down insulation is that it loses much of its ability to maintain warmth when it gets wet, but the bag’s premium 850+ fill Ultra-Dry Down performs differently. Ensuring consistent thermal performance, a hydrophobic treatment enables the insulation to stay dry longer and dry faster if it should become wet than traditional down insulation. The bag uses lightweight 10 denier nylon on the exterior shell fabric and a 7 denier nylon interior lining. The bag uses sewn-though construction to save weight and keep insulation from migrating and creating cold spots. An insulated hood bolsters warmth. The Sea to Summit Spark SpI sleeping bag is available in your choice of Regular (fits up to 6’ 0”) and Long (fits up to 6’ 4”) size options.
Incredibly lightweight and compressible, the Sea to Summit Spark SpI is ideal for ultra-lightweight warm-weather backpacking or thru-hiking. It weighs right around a pound, features weather-resistant treated down insulation, and has a temperature rating of 40 Degrees F. Renowned for their efficiency in retaining heat and compressible properties, the feathers and fibers of down have an incredibly soft, comfortable feel and, despite advances in synthetic materials, continue to provide the best warmth-to-weight ratio of any insulation available. The one inherent weakness of down insulation is that it loses much of its ability to maintain warmth when it gets wet, but the bag’s premium 850+ fill Ultra-Dry Down performs differently. Ensuring consistent thermal performance, a hydrophobic treatment enables the insulation to stay dry longer and dry faster if it should become wet than traditional down insulation. The bag uses lightweight 10 denier nylon on the exterior shell fabric and a 7 denier nylon interior lining. The bag uses sewn-though construction to save weight and keep insulation from migrating and creating cold spots. An insulated hood bolsters warmth. The Sea to Summit Spark SpI sleeping bag is available in your choice of Regular (fits up to 6’ 0”) and Long (fits up to 6’ 4”) size options.
in 7 offers
The lowest price for Sea to Summit Spark SPI Sleeping Bag (Regular) right now is $209.00 at Snowys Outdoors, compared across 5 retailers.
The all-time low was $209.00 on 24 May 2026. That's the lowest price we've ever tracked — a great time to buy.
Prices last updated 29 June 2026.
Last updated at 29/06/2026 15:31:02
Spark SP0 Sleeping Bag (14 °C)
Free 60-day returns
Spark SP2 Sleeping Bag (4 °C)
Free 60-day returns
Spark SP3 Sleeping Bag (-2 °C)
Free 60-day returns
Sea to Summit Sea to Summit Spark SP1 Regular
Delivery $19.99
Sea to Summit SPARK SPIII
Free delivery between 2–10 July
Sea to Summit Spark III Ultralight Sleeping Bag -8°C REGULAR / Yellow | Boss Outdoor
Sea To Summit Spark Ultralight Sleeping Bag 5°F | -15°C Regular
originally posted on moosejaw.com
That's the question I had to seriously consider after spending the first night inside my Sea to Summit Spark IV 5F sleeping bag.Was it love at first sight? Maybe.Was it love after my first night in the wild in windy subfreezing temperatures? Absolutely.To say I was "warm" would be a disservice to this magical bag. I felt held and safe and oh so comfortable."It's freezing outside?" I thought to myself. "Hmmm, it's like sitting in a toasty room heated by a sweet crackling fire inside my bag."And when the wind whipped up outside, I just snugged down the hoodie and slept the night away ... even when the rabid raccoon outside my tent started yelling at me!From a context standpoint, I'm a bikepacker, I'm a little over 5/10", and I'm a side sleeper.- At 1 lb ... MoreThat's the question I had to seriously consider after spending the first night inside my Sea to Summit Spark IV 5F sleeping bag.Was it love at first sight? Maybe.Was it love after my first night in the wild in windy subfreezing temperatures? Absolutely.To say I was "warm" would be a disservice to this magical bag. I felt held and safe and oh so comfortable."It's freezing outside?" I thought to myself. "Hmmm, it's like sitting in a toasty room heated by a sweet crackling fire inside my bag."And when the wind whipped up outside, I just snugged down the hoodie and slept the night away ... even when the rabid raccoon outside my tent started yelling at me!From a context standpoint, I'm a bikepacker, I'm a little over 5/10", and I'm a side sleeper.- At 1 lb 15 oz, the bag has excellent weight to value ratio, and was barely noticeable in my bike's seat bag. With its ultra dry 850+ loft, it doesn't stuff down as small as say my 20F quilt, but that's to be expected ... and if it keeps the shivering at bay, I'm happy to relocate other seat bag items accordingly.- I opted for the Regular (vs Long), and - if I had to do it over - I'd swap for the long. The bag says it fits up to 6' height, which is true, but as a side sleeper this leaves more of my arms and head exposed than I'd ideally like.- As a side sleeper and someone who rotates sides throughout the night, I appreciate that that the 5F and 18F bag are designed as "broader mummy," allowing me do my turning, turning, turning with limited resistance.Oh and the UL 10 denier nylon give me peace of mind. Not having to worry about a little condensation in the tent or water falling from the sky ruining my warmth is a big plus.So, do I recommend? Highly and without reservation. It's an investment, for sure, but one I think you'll be glad you made ... for many, many years (and trips) to come!
originally posted on snowys.com.au
The bag is extremely high quality. The design, materials and construction are all top notch. No question that the price point is justified.However be aware that the temperature rating is over-stated. In my experience, a normal adult man should expect to be comfortable (in thermals / beanie) down to about 5 degrees. That's with a suitable pad. If that's what you need then I'd recommend unreservedly.
originally posted on snowys.com.au
Owned this now for 12 months now. Super lightweight and packs down small. Had this in +3c degrees min sleeping in a wool T-shirt and wool boxers. I threw my down jacket in to take up air space over my chest and was perfectly fine within a single wall tent. At +6c I ended up using the sleeping bag like a quilt to let a bit of air in. Zips are good quality, but you have to be conscious of them catching if your too rough or quick. The neck baffle and head cover work really well. This really makes a difference in warmth factor. If I went full thermals and clothes/socks (which is how the bag ratings are set) I would have been way too hot, so I would say the bag rating is bang on for -2c to -5c if your layered up, you will be toasty at the comfort rating. Can’t stress the ... MoreOwned this now for 12 months now. Super lightweight and packs down small. Had this in +3c degrees min sleeping in a wool T-shirt and wool boxers. I threw my down jacket in to take up air space over my chest and was perfectly fine within a single wall tent. At +6c I ended up using the sleeping bag like a quilt to let a bit of air in. Zips are good quality, but you have to be conscious of them catching if your too rough or quick. The neck baffle and head cover work really well. This really makes a difference in warmth factor. If I went full thermals and clothes/socks (which is how the bag ratings are set) I would have been way too hot, so I would say the bag rating is bang on for -2c to -5c if your layered up, you will be toasty at the comfort rating. Can’t stress the importance of having a quality INSULATED sleeping pad to match. This is a technical sleeping system and designed to keep you warm, so spaciousness and freedom are secondary. As a side sleeper there is a bit more getting used to being cocooned but the hiking weight is worth it which was my number one requirement. Very good product for the price, excellent weight for hiking, highly recommended.
| Snowys Comfort Rating | 9 °C |
| Lower Limit | 5 °C |
| Shape | Mummy |
| Max. User Height | 183 cm |
| Internal Girth | 150 cm Chest | 130 cm Hip | 88 cm Foot |
Spark SP0 Sleeping Bag (14 °C)
Free 60-day returns
Spark SP2 Sleeping Bag (4 °C)
Free 60-day returns
Spark SP3 Sleeping Bag (-2 °C)
Free 60-day returns
Sea to Summit Sea to Summit Spark SP1 Regular
Delivery $19.99
Sea to Summit SPARK SPIII
Free delivery between 2–10 July
That's the question I had to seriously consider after spending the first night inside my Sea to Summit Spark IV 5F sleeping bag.Was it love at first sight? Maybe.Was it love after my first night in the wild in windy subfreezing temperatures? Absolutely.To say I was "warm" would be a disservice to this magical bag. I felt held and safe and oh so comfortable."It's freezing outside?" I thought to myself. "Hmmm, it's like sitting in a toasty room heated by a sweet crackling fire inside my bag."And when the wind whipped up outside, I just snugged down the hoodie and slept the night away ... even when the rabid raccoon outside my tent started yelling at me!From a context standpoint, I'm a bikepacker, I'm a little over 5/10", and I'm a side sleeper.- At 1 lb ... MoreThat's the question I had to seriously consider after spending the first night inside my Sea to Summit Spark IV 5F sleeping bag.Was it love at first sight? Maybe.Was it love after my first night in the wild in windy subfreezing temperatures? Absolutely.To say I was "warm" would be a disservice to this magical bag. I felt held and safe and oh so comfortable."It's freezing outside?" I thought to myself. "Hmmm, it's like sitting in a toasty room heated by a sweet crackling fire inside my bag."And when the wind whipped up outside, I just snugged down the hoodie and slept the night away ... even when the rabid raccoon outside my tent started yelling at me!From a context standpoint, I'm a bikepacker, I'm a little over 5/10", and I'm a side sleeper.- At 1 lb 15 oz, the bag has excellent weight to value ratio, and was barely noticeable in my bike's seat bag. With its ultra dry 850+ loft, it doesn't stuff down as small as say my 20F quilt, but that's to be expected ... and if it keeps the shivering at bay, I'm happy to relocate other seat bag items accordingly.- I opted for the Regular (vs Long), and - if I had to do it over - I'd swap for the long. The bag says it fits up to 6' height, which is true, but as a side sleeper this leaves more of my arms and head exposed than I'd ideally like.- As a side sleeper and someone who rotates sides throughout the night, I appreciate that that the 5F and 18F bag are designed as "broader mummy," allowing me do my turning, turning, turning with limited resistance.Oh and the UL 10 denier nylon give me peace of mind. Not having to worry about a little condensation in the tent or water falling from the sky ruining my warmth is a big plus.So, do I recommend? Highly and without reservation. It's an investment, for sure, but one I think you'll be glad you made ... for many, many years (and trips) to come!
The bag is extremely high quality. The design, materials and construction are all top notch. No question that the price point is justified.However be aware that the temperature rating is over-stated. In my experience, a normal adult man should expect to be comfortable (in thermals / beanie) down to about 5 degrees. That's with a suitable pad. If that's what you need then I'd recommend unreservedly.
Owned this now for 12 months now. Super lightweight and packs down small. Had this in +3c degrees min sleeping in a wool T-shirt and wool boxers. I threw my down jacket in to take up air space over my chest and was perfectly fine within a single wall tent. At +6c I ended up using the sleeping bag like a quilt to let a bit of air in. Zips are good quality, but you have to be conscious of them catching if your too rough or quick. The neck baffle and head cover work really well. This really makes a difference in warmth factor. If I went full thermals and clothes/socks (which is how the bag ratings are set) I would have been way too hot, so I would say the bag rating is bang on for -2c to -5c if your layered up, you will be toasty at the comfort rating. Can’t stress the ... MoreOwned this now for 12 months now. Super lightweight and packs down small. Had this in +3c degrees min sleeping in a wool T-shirt and wool boxers. I threw my down jacket in to take up air space over my chest and was perfectly fine within a single wall tent. At +6c I ended up using the sleeping bag like a quilt to let a bit of air in. Zips are good quality, but you have to be conscious of them catching if your too rough or quick. The neck baffle and head cover work really well. This really makes a difference in warmth factor. If I went full thermals and clothes/socks (which is how the bag ratings are set) I would have been way too hot, so I would say the bag rating is bang on for -2c to -5c if your layered up, you will be toasty at the comfort rating. Can’t stress the importance of having a quality INSULATED sleeping pad to match. This is a technical sleeping system and designed to keep you warm, so spaciousness and freedom are secondary. As a side sleeper there is a bit more getting used to being cocooned but the hiking weight is worth it which was my number one requirement. Very good product for the price, excellent weight for hiking, highly recommended.
This bag is amazing but you need to be ready to make some compromises. Here are some pros and cons I foundPros:-Extremely light and compact, this bag is ideal for long backpacking-Runs surprisingly warm, I used it at 2c in just a pair of boxers and woke up from being too hot.-The material even though its super light and thin still feels pretty sturdy and durableCons:-Sleeping in this was like sleeping in a warm plastic bag. The bag sticks to your skin and does not feel comfortable to the skin overall, but I suppose this can be overcome with a liner or by wearing some base layers-The zipper kept getting caught on the fabric but also since it only runs half the length of the bag, it made it pretty difficult to ventilate and there is no easy way to use ... MoreThis bag is amazing but you need to be ready to make some compromises. Here are some pros and cons I foundPros:-Extremely light and compact, this bag is ideal for long backpacking-Runs surprisingly warm, I used it at 2c in just a pair of boxers and woke up from being too hot.-The material even though its super light and thin still feels pretty sturdy and durableCons:-Sleeping in this was like sleeping in a warm plastic bag. The bag sticks to your skin and does not feel comfortable to the skin overall, but I suppose this can be overcome with a liner or by wearing some base layers-The zipper kept getting caught on the fabric but also since it only runs half the length of the bag, it made it pretty difficult to ventilate and there is no easy way to use this as a blanket in warmer weather-The hip area was a bit tight and didn't allow for easy rolling over
Weight and volume were awesome! I did not use the accompanying compression sack as it took several minutes to stuff and was too small. I was afraid to break the feathers. I used a larger stuff sack and placed under the Bear vault which then compressed it and it made a good base.Feather distribution was disappointing as there were too many feather free spaces and I got cold on a few nights. It was ok as I wore my silks. I just used the bag for the John Muir Trail which I finished last week.Suggestion would be to add just 1 or 2oz of feathers and improve distribution even at the cost of additional weight. Also increase the size of the compression sack by 10% to facilitate stuffing.
The spark series bags have yet to disappoint! Note- there are a few compromises for the best performance, like a very light gauge zipper, 1/2 zip length, and a strong taper for the feet. If you are extremely claustrophobic and like to sleep like a starfish you may want a heavier bag for comfort- but that one small issue aside this bag is incredible! I find myself bringing it along on long backcountry day missions for a little extra insurance should I need to spend an unplanned night out! It is so light and small it fits in any kit, even ultralight bikepacking gear. Would recommend this bag to anyone!
The Spark SP II really shines is in its weight and packing size. At just 1.21 pounds for a size long, it is among the lightest of the 3-season sleeping bags, and I have cinched it down even smaller than pictured. Spark II has an awesome warmth-to-weight ratio, and is a quality build with premium 850+ fill power goose down.Because of how I pack, I find this product so useful in saving weight and space when I have to accommodate other things.I have 3 sleeping bags, the other two have more specific use cases. I really love it when I can pack this one for my trips.
Bought this degree rating for weight conservation for multiple 3 day guides and 8 day loops in the upper Northeast US region. Has been tested during 40* degree highs with lower temps dipping around 7* degrees at night (real feel Neg -7 to -12).Here's how I do it.... Bag is realistically rated around 18 to 25*ish because I'm a hot sleeper. I used a reactor liner on the decent night's above 10 degrees without base layers, down booties and puffy,fishing wader liners and accessories until the teens and single digits and still was very selective on which layers!!! Keep the loft up on the bag and it holds very well.Unfortunately I don't have an Ether XT Extreme (yet) to pair this bag with, so I use a competitor 4" 4.2 R- value with Z-pad or B/A Bio foam, tenting on snow ... MoreBought this degree rating for weight conservation for multiple 3 day guides and 8 day loops in the upper Northeast US region. Has been tested during 40* degree highs with lower temps dipping around 7* degrees at night (real feel Neg -7 to -12).Here's how I do it.... Bag is realistically rated around 18 to 25*ish because I'm a hot sleeper. I used a reactor liner on the decent night's above 10 degrees without base layers, down booties and puffy,fishing wader liners and accessories until the teens and single digits and still was very selective on which layers!!! Keep the loft up on the bag and it holds very well.Unfortunately I don't have an Ether XT Extreme (yet) to pair this bag with, so I use a competitor 4" 4.2 R- value with Z-pad or B/A Bio foam, tenting on snow and dirt with tyvek so far(for reference).The Good: The bag held warmth way better than expected. I believe the DWR and U/D Down in this bag is spot on and look forward to seeing how they will better this technology further in 2022.Water bottle dumped on foot box and i literally shook it off like a duck. NO absorption whatsoever for now! Usage with proper care is KEY! Foot box is pretty roomy even when crammed from sliding, but stays pretty warm with proper layering for the conditions and staying away from the tent walls.The "not so Bad" but really annoying: This bag is Slick... like Owl excrement. Almost any kind of angle will have you playing slip and slide on your mat. I wear merino base layers and feel like I'm sleeping on a ice sometimes. Pull yourself up...slide back down aaand repeat. Wake up in a ball at the foot of the tent but works magic on your abs!!! So at the end of the day ground dwellers are hunting for almost perfectly flat sites or getting perfectly chiseled abs from crunches! Win Win!! Hammocking with air mat isn't much of an issue. I've had this issue with most of the newer bags I have bought since 2014 that use the lighter nylon. So it's a love and hate kind of relationship. Slight zipper catch on the baffle (really slight) and leaking by shoulder/neck area,but could be contributed to me tossing and turning like an angry groundhog. Neck and hood baffles are great though. Well made and stuffed with plenty of room to cinch up, but you're not stuffing your big head AND your deluxe pillow at the same time. Not happening. I tried, but it's not a deal breaker either! Shoulder width could be better please! I'm thinking by an extra 1 to 1.5"inchs, added for us working fellas on trail with the broad shoulders...No worries, we can handle the extra weight and would appreciate that extra "wiggle" room!(Wink Wink)... Ohhhh yeah. Why did you stop the zipper there again? Please let me open up that footbox! Sometimes we like to open 'er up in the morning like a big ole' blanky with our breakfast! Give the people what they need!!! No fuss Breakfast blankies!This bag really could be 5 stars if I wasn't losing sleep over it...I'm not evil either...so 4.675 stars for overall functionality,Baffle upgrades and quality control with the down. Still a great piece of gear for the money and c'mon its Sea to Summit! Enough said. Yes I recommend this product as a professional,but don't condone my actions with product specifications. Please do not do as I do unless you prepare and train as I do...Thank you!!! Stay Safe and Hike your hike, not mine!!!
This ultralight sleeping bag itself is very comfortable and perfect for its temperature range. HOWEVER, the zipper makes this sleeping bag unusable. The zipper is so small and flimsy that itsnags every single time I use it. Because of this I have had to mend the sleeping bag material around the zipper several times due to tares and at one stage the zip separated which was very difficult to mend. I am very disappointed and although I love the sleeping bag itself, this issue makes me want to give it 0 stars if this was possible. I appreciate the ultralight weight of this bag, but for a few grams extra a more robust zipper system would make this sleeping bag 5 stars.
The tall fit is perfect for me as I'm 189cm. The mummy fit is efficient, but not constricting or uncomfortable.With the -8°c fill, it has proven perfectly comfortable at 0° this far.The compressibility and weight was a big factor for me, and this is top for UL backpacking and bikepacking in 3 season conditions thus far. For bikepacking the back for easily in my saddlebag, and firmly in my handlebar bag.The zipper is top-notch and given the manufacturer, I will expect no issues in the future.
| Snowys Comfort Rating | 9 °C |
| Lower Limit | 5 °C |
| Shape | Mummy |
| Max. User Height | 183 cm |
| Internal Girth | 150 cm Chest | 130 cm Hip | 88 cm Foot |
