Sea to Summit Spark SP I



This is an ultra-ultralight sleeping bag with a short…

Rating: rated 4 of 5 stars
Source: bought it new
Price Paid: 284 EURO


This is an ultra-ultralight sleeping bag with a short zip. Use it when you want to save weight and if you are prepared to sacrifice some comfort.


  • Ultralight
  • Warm for its weight


  • Space is lost lengthwise when fully closing the hood
  • Cannot be used as a blanket when it is hot

I am 189cm (6'2"). This bag (size long) weighs 428g (15.097oz) without the stuff sack. It is the lightest sleeping bag I could find.

This is different for every person. I would say the temperature rating is OK. I am a very cold sleeper so I can use this bag even when it is around the lower limit of 8°C|46°F. I don't mind being somewhat cold, but I will rather put on all available clothes and wake up every now and then before carrying a heavier bag. When it gets cold at home, I sleep outside on the balcony to see how low I can go. Below freezing point I definitely had to give up!

Fit & Comfort:
The length is just enough for me. It has a narrow fit. Footroom is OK. When it gets cold I wear socks because I will always touch some cold spots with my toes. 

When it is cold and I fully close the drawcord, this reduces the size lengthwise somewhat, but it is acceptable.

Entry & Exit:
Because of the really short zip, it takes some time to wiggle in and out of the bag.

Because of the really short zip, you cannot open the bag and use it as a blanket. You can only be inside or outside. Opening the zip will not really help if it is too warm.

It offers some resistance to spray, but it must be used under a tarp or in a tent if it rains.

I guess it packs down in relation to its weight, which is very small. I never use the stuff sack.

Ease of Use:
Getting in and out takes some wiggling.

Construction & Durability:
I have used it about 100 times and it shows no wear. You have to be careful because it is super light and therefore somewhat fragile.