Sea to Summit Trek TK II

Summary

Excellent down bag for a variety of conditions. It's lightweight, packs down small, does better in wet weather than other down bags, and is very comfortable.

This is the fourth backpacking sleeping bag I've purchased, and the second down bag. I purchased it when backpacking in Chile in 2012, realizing that the very lightweight synthetic bag that I had with me at the time would not keep me warm further south in Patagonia. I used it camping in all conditions in southern Chilean Patagonia, as well as many other places in South America and the U.S., and this bag has proven itself again and again as one of the best pieces of gear that I own.

One of the most notable points about this bag is how small it compacts. Sea to Summit makes excellent compression sacks, and they include a custom compression sack with the bag (as well as a storage sack and a cotton sack to wash the bag in). When fully cinched down, the bag compresses to a ball about 7" in diameter. When I compare this to my other down bag, which was more expensive and supposedly warmer than this Sea to Summit Trek II, the other down bag was about double the size of the Trek II when fully compressed. 

The Trek II does an excellent job in semi-cold weather. I've used this bag in snowy conditions numerous times, though probably not much lower than 20 deg F, and slept warmly. This bag seems to be warmer than other bags that are similarly rated — I'm not sure how they do that, but Sea to Summit's down or design does a better job than my similarly temperature-rated Sierra Designs synthetic bag and my RAB down bag. I've also gotten it a little wet and it was not too bad from a comfort or temperature perspective. In contrast, my RAB bag seems to get wet very easily and loses all of its heat when it does.

The boxy design is very comfortable if you don't like the full mummy-style sleeping bags. The hood cinches down well around your face, and helps a lot in colder conditions. And the tiny pocket near the top is great for keeping small items easily accessible. I keep a pair of small earplugs in there so I have them when I am sleeping next to friends that snore.

Lastly, I'll point out that the Sea to Summit bags have zippers that are compatible with one another for certain designs, if you get one Left zip bag and one Right zip. With this, my wife got the Sea to Summit Trek III, which is a slightly warmer bag than the Trek II, and we can zip the two bags together. The combined body heat with two bags connected adds a lot of warmth.

Thank you Sea to Summit for making an excellent product.