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Altitude Women's Down Sleeping Bag (25°F & 15°F)

This bag can take you from sea to summit

$379.00 – $439.00

Sleeping Bag Temperature Ratings Explained

The EN Rating scale is a scientific test to determine the warmth of a sleeping bag. The test produces a Lower rating (for male sleepers) and a Comfort rating (for female sleepers). Both are listed in the features table on the product page.

A unisex sleeping bag with a Lower limit of 14ºF means a man should be comfortable down to air temperatures of 14ºF. The same bag will also have a Comfort limit, in the realm of 27°F, so a woman would be comfortable down to an air temperature of 27ºF. These ratings require a sleeping mat with an R-Value appropriate for expected ground temperatures – without this, the sleeping bag itself is unlikely to keep the sleeper warm enough.

A variety of factors impact sleeping bag warmth - the above temperatures are merely guidelines, not guarantees. It’s important to think of a sleeping bag, an appropriately insulating sleeping pad and a liner as a sleep system. For example - if you plan on sleeping in nighttime air temperatures of 27ºF / -3°C, choose a bag with a gender-appropriate rating of 23°F / -5°C, plus a sleeping mat with an R-Value of 2.5 to 3, and consider a Reactor thermal liner.



Incredibly versatile, the Altitude™ women’s down sleeping bag is snug and cozy when it’s cold outside, cool and ventilated when the weather warms, shaped to match your natural sleeping position for comfort anytime, and light enough to carry anywhere.

It could just be the perfect sleeping bag for women adventurers.

Technical Features

750+ Loft Ultra-Dry Down™

The second highest-lofting down used in any of Sea to Summit’s sleeping bags. 750+ Fill Power indicates that one ounce (30g) of down will re-expand to over 750 cubic inches after compression. Higher loft means that less down can be used to achieve the same temperature rating – important for performance sleeping bags. The loft and down quality/composition are independently tested by the International Down and Feather Laboratory (IDFL) – a copy of the certification is supplied with every Sea to Summit sleeping bag.


The down is responsibly sourced and RDS certified and treated with the environmentally-friendly Ultra-Dry Down™ treatment.


All of which means you can rest easy.

Responsible Down Standard (RDS)

All Sea to Summit sleeping bags use only down which is certified according to the Responsible Down Standard. The RDS is helping shift the entire down and feather industry towards more humane animal rearing and handling practices. Overseen by the industry leading Textile Exchange, the RDS requires independent, third-party assessments of all aspects of animal rearing and handling throughout the entire supply chain. By using only down that meets the audited requirements of the RDS, we can have confidence that each phase of the collection process has been completed with the welfare and ethical treatment of waterfowl in mind.

To learn more about RDS, visit

Thermolite® HL-1

Thermolite® HL-1 is part of the family of Thermolite® materials used in Sea to Summit sleeping bags, sleeping bag liners and sleeping mats. HL-1 high loft insulation is a fiberfill constructed with a unique 3D crimp of hollow-core and solid fibers, which provides excellent lightweight warmth with superior durability. The Thermolite insulation lofts up inside the Air Sprung Cells™ of our sleeping mats to prevent convective heat loss from your warm body to the cold ground.

Free Flow Zip

Our Free-Flow triple-zip design ensures your sleeping bag retains maximum warmth and efficiency when needed and multiple ventilation options when it's not. 

The half-zip on the right side of the bag (left side on women's bags) provides freedom of movement for both arms, additional ventilation and allows the top third of the bag to be folded down as a mini quilt when the mercury climbs higher than expected.

Tech Specs

Product Details

Best Use
Comes With
Ultra-Sil™ compression bag and storage cell
Ultra-Dry Down 750+ Loft
Shell Fabric
Lightweight 20D Nylon Shell
Zip Options
Free-Flow zipper system
altitude-womens-down-sleeping-bag-25-f-15-f-regular.svg altitude-womens-down-sleeping-bag-25-f-15-f-long.svg
Altitude 1
2lbs 6.1oz / 1080g
6.5 L
S - 10L to 3.3L
18.3oz / 520g
5 ft 7 in / 170 cm
2.5 Season
25°F / -4°C
Altitude 1
2lbs 9.3oz / 1170g
8.3 L
S - 10L to 3.3L
20.5oz / 580g
6 ft / 183 cm
2.5 Season
25°F / -4°C
Altitude 2
2lbs 13.2oz / 1280g
8.1 L
M - 14L to 4.5L
25.4oz / 720g
5 ft 7 in / 170 cm
3 Season
15°F / -10°C
Altitude 2
3lbs 1oz / 1390g
9.8 L
M - 14L to 4.5L
28.2oz / 800g
6 ft / 183 cm
3 Season
15°F / -10°C


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