How to Choose Sleeping Bags for Backpacking
Sea to Summit Altitude Atl 25 Sleeping Bag - Women's
This product is not available.
Creating a balance of comfort and weight for backpackers, the Sea to Summit Altitude AtI 25 sleeping bag offers generous space while still providing the thermal efficiency you need.
Shop similar productsKey Details
Fill
750-fill-power UltraDry Down
Temperature Rating (F)
25 degrees (F)
- Women-specific technical tapered rectangular shape creates the perfect balance of space and adaptable warmth
- 750-fill-power UltraDry Down™certified to the Responsible Down Standard (RDS)
- Extra down throughout and THERMOLITE® panels under the foot area provide additional warmth; anatomically shaped footbox allows maximum down lofting
- Vertical chest baffles prevent down migration and cold spots
- Generously sized hood and dual cord adjustment offers maximum warmth retention
- Lightweight 20-denier nylon shell and lining fabrics offer a minimal packed size and maximum breathability
- Free-Flow half-zip left side, full-length 2-way #5 YKK zip right side and separate foot zips allow maximum ventilation and use as a quilt
- Includes Ultra-Sil™ compression bag for compact storage
- Oversize draft tube with antisnag materials
- Oversize neck draft tube with dual adjustment system
- Large internal security pocket
- This bag is designed to easily zip with another (second sleeping bag sold separately)
Imported.
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 |
|---|---|
| Tested Lower Limit | 11 degrees (F) - EN |
| Tested Comfort | 25 degrees (F) - EN |
| Temperature Rating (F) | 25 degrees (F) |
| Temperature Rating (C) | -4 degrees (C) |
| Shell | 20-denier nylon |
| Zipper Location | Right |
| Insulation Type | Down |
| Water-Resistant Down | Yes |
| Fill | 750-fill-power UltraDry Down |
| Lining | 20-denier nylon |
| Sleeping Bag Shape | Semirectangular |
| Stuff Sack Size | Unavailable |
| Stuff Sack Volume | Unavailable |
| Compressed Volume | Unavailable |
| Gender | Women's |
| Sustainability | Down certified to the Responsible Down Standard (RDS) |
Buying Advice
Review this Product
Adding a review will require a valid email for verification
Customer Images
Kayla K.
This bag is so cozy
1 year ago
[This review was collected as part of a promotion.] This bag is so cozy and the color is beautiful. The zippers on both sides are such a great thing for me as I typically sleep facing the opposite side the zippers are on other bags and my dog crawls in to sleep inside with me. There’s plenty of room for her to do that with this bag also. We took it on our first adventure backpacking to a fire tower overnight and it was plenty warm in the 20s with my liner, wearing just a base layer. I can’t wait to take it on more adventures when the weather warms up and see how it holds up but I’m already very happy with the purchase!
Originally posted on Sea to Summit
Megan G.
Money Well *Slept* ;)
2 years ago
[This review was collected as part of a promotion.] This is hands down THE best sleeping bag I've ever owned! Well worth the investment!! I am obsessed with the color! & Its performance is immaculate! The zippers are easy to zip up & down without worry of snagging. & Even when the temps dropped during the night on my last camping trip, this fluffy bag kept me comfy & cozy all night without needing extra layers or a heater in my tent! I love my Sea to Summit sleeping system!!! (I only wish my new Aeros Down Pillows had arrived in time for this last trip!)
Originally posted on Sea to Summit
Meg
Great bag!
3 years ago
This bag is really comfy and cozy! It feels very light but definitely keeps the heat in! My sleeping pad failed on me on night 2 of a 2 night trip and the bag still kept me reasonably warm. I think I would pair it with one of the liners for Alberta's unpredictable shoulder seasons, but I love how versatile it is. I have tried zipping it together with my boyfriend's bag and we were very comfy, almost too warm! If I feel claustrophobic in it I simply unzip the half zip on the off side and it gives my arms a little room to splay out. After about 5 uses I am noticing some of the down coming out so hopefully this is just a normal thing and won't turn into a big issue. I also love the color (not pink!! Woohoo!)
Originally posted on Sea to Summit
Cathy T.
Best Sleeping Bag! Buy it!
2 years ago
I've had this sleeping bag for over 3 years (still going strong) and its been everywhere with me! From car camping trips to multi-day treks in all different climates, it will keep you comfy with all the different options. I thought I would want the lighter weight and more compact Flame Sleeping Bay by sea to summit, (and I am sure I would like it) however I am so glad I got the Altitude Bag instead. I love all of the options and configurations (mostly being able to unzip the foot box and stick my feet out when I want. To me It is worth the extra weight ! The bag keeps me warm when I need it and I can change the set up so I can stay cool if I need to as well. If you are considering this you will not regret buying it!
Originally posted on Sea to Summit
Blake M.
Pretty good
1 year ago
[This review was collected as part of a promotion.] The sleeping bag is made well, very comfy feels cozy, and not noisy. The width was great and not too snug sleeping in undergarments but would have been crowded with heavy sleepwear. I wish I would’ve ordered a longer and colder bag. Sleeping Id roll further into the bag and the foot box was cramped lengthwise (im 5’6”). I did not attempt to use the bag solo nor would I because it was so cold, icy, & damp. I used a liner (game changer!) and a secondary sleeping bag unzipped on top as a blanket.
Originally posted on Sea to Summit
Jessica D.
Plushy and Cozy
4 years ago
I'm obsessed with this sleeping bag for a couple of reasons. 1. the color is great and one of my favorite colors! 2. I have the 15 degree, and it's so cozy and plushy. My only comment is that it doesn't back down as small as the 25 degree, but it's something I'm willing to sacrifice for the additional plush. I'm a side sleeper and tend to roll from side-to-side, and this allows plenty of room without getting wrapped up or trapped.
Originally posted on Sea to Summit
Pattie
Altitude Women's Down Sleeping Bag 15°F
1 year ago
Wow, I went from a summer flannel sleeping bag that I would freeze in to a cascade of down comfort comparable to nothing you could possibly imagine. I'm is awe as a first time user. It takes a while to wrap your head around the price, but once you jump in, there is no turning back. I highly recommend! I also purchased a liner that can be used alone or with the down bag.
Originally posted on Sea to Summit
Sheridan B.
Love this sleeping bag!
4 years ago
I absolutely love this bag. I stay far warmer in this bag in colder temperatures than I have with zero degree bags in the past. It's certainly not the lightest 15 degree bag, but I've found the little bit of extra weight to be well worth it for the warmth provided as well as the versatility of the zippers for the nights that aren't quite as cold. No complaints!
Originally posted on Sea to Summit
Floyd D.
Very nice sleeping bag!
4 years ago
We bought the men's and women's version of this bag and we love them. We used them to replace our 30 degree bags that were about the same packed size. The only drawback is that they are very expensive. They are roomier than our older bags which makes it easier to move around in the bag without feeling confined.
Originally posted on Sea to Summit
Cassie L.
Obsessed!
1 year ago
[This review was collected as part of a promotion.] This sleeping bag is truly my holy grail! It’s comfortable, versatile, warm, and beautiful! I’m a side sleeper who tosses and turns a lot and this bag didn’t make me feel constricted at all. My feet also tend to get warm so I really liked the zipper just for the end of the bag. Highly recommend!
Originally posted on Sea to Summit
1 - 10 of 30 Reviews