Be prepared for the unpredictable with our adaptable Ascent™ Series bags.

Light, warm, comfortable and most importantly, adaptable. Offering the perfect backpacking balance of comfort vs weight, our Ascent™ Series sleeping bags have more space than traditional mummy bags, yet still provides the thermal efficiency you need when exploring above the tree-line.

The EN13537 is a European standard for sleeping bags that provides three temperature levels to help guide you when choosing a bag.

Comfort The temperature at which a standard woman can expect to sleep comfortably in a relaxed position. If you are female or consider yourself a cold sleeper, use this rating to decide the coldest temperature the sleeping bag is suitable for. We emphasise the Comfort temperature for our women’s specific sleeping bags.

Lower Limit The temperature at which a standard man can sleep for eight hours in a curled position without waking. If you consider yourself a warm sleeper, use this rating to decide the coldest temperature the sleeping bag is suitable for. We emphasise the Lower Limit temperature for all our unisex sleeping bags.

Extreme This is a survival only rating for a standard woman. Between the lower limit and the extreme rating a strong sensation of cold must be expected and there is a risk of health damage due to hypothermia. This is an extreme survival rating only; we do not recommend you rely on this rating for normal use.

750+ Loft

750+ Fill Power indicates that 1 oz 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.

ULTRA-DRY Down™

ULTRA-DRY Down™ is a permanent nano-level water repellent polymer treatment applied to our down which protects it from external moisture and condensation from inside the bag virtually eliminating the negative effects moisture has on down.

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 responsibledown.org

Down and synthetic bags identified with our zip coupling symbol use a 165cm #5 YKK full-length zip which allows a unisex left-handed and women’s specific right-handed bag to pair together.

Designed to pair side by side, each person sleeps in their own bag enabling each of you to take advantage of your bag’s unique insulation zones, hood and footbox features—perfect for cosy adventures for two. Bags with full-length #5 YKK zips on both sides can also be coupled together with other pairing bags.