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New Sea to Summit Sleeping Bags - Taking comfort and versatility to a new level

New Sea to Summit Sleeping Bags - Taking comfort and versatility to a new level

The concept of sleep systems – sleeping mats, sleeping bags, liners and pillows designed to harmonize together – was pioneered by Sea to Summit to provide a better night’s sleep. This year, we’re taking the system concept to the next level. For 2024, the Sea to Summit design team has created a range of sleeping bags that focus on even greater comfort and versatility, so you can wake rested and refreshed, whatever your adventure.

Your sleeping bag is the core of your sleep system. Sea to Summit offers a range of options for a variety of adventures.

Sea to Summit sleeping bags encompass a range of temperature ratings, plus a variety of shapes, ventilation options and overall weights and packed sizes. The construction and materials include the following:

  • Vertical baffles in the torso which prevents the down shifting towards the sides of the bag when you move in your sleep
  • PFC and PFAS-free hydrophobic Ultra-Dry Down treatment to keep the down from absorbing moisture and allowing it to dry more quickly
  • PFC and PFAS-free DWR finishes on the shell to help repel external moisture
  • Recycled materials wherever possible

Warmth, weight, ventilation, and comfort

For certain pursuits – backpacking, bike packing, ski touring – light weight and small packed volume are key. The Spark Down Sleeping Bag and Women’s Spark Down Sleeping Bag are extremely light and packable. Cleverly constructed using featherweight 10 denier fabrics and super-compressible 850+ loft down, the shape is designed to retain warmth while still allowing you room to move. We’ll cover what’s new with the Spark bags in 2024 a little bit further down


Backcountry users who demand performance and comfort across a broad range of temperatures will love the flexibility and function of the Ascent Down Sleeping Bag and Women’s Ascent Down Sleeping Bag. Upgraded to goose down for 2024 and featuring recycled nylon fabrics, the Ascent is truly one of the most versatile performance sleeping bags on the market (more about which in a moment).

And for those adventurers who prefer counting sheep over grams, the 650+ fill power Trek Down Sleeping Bag and Women’s Trek Down Sleeping Bag offer a comfort-oriented, adaptable sleep environment that is ideal for camping, travel and occasional short backpacking trips. Available in various temperature-rating options, the broader cut and uprated Free-Flow system make the Trek a perfect companion for comfortable nights in less technical environments.

Warmth and Comfort

Published sleeping bag specifications and ratings only tell part of the story. Elements such as technical-shaped hoods and draft tubes play a vital role in retaining warmth in the real world, outside of the lab. Sea to Summit’s designers have paid particular attention to construction, especially in performance bags such as the Spark and Ascent.

Specifications also give little indication of how well you will actually sleep in a particular sleeping bag. Comfort and usability come from the tactile feel of a fabric or the ease of use of a zipper. The 2024 Spark and Women’s Spark have received significant upgrades in the breathability of the liner fabrics, the water-repellence of the hood and footbox shell material and the durability of the zippers used.

Until now, extremely lightweight and versatility were seen as an either/or choice. Not anymore. For 2024, Sea to Summit introduces the Pro version of its Spark series – the Spark Pro Down Sleeping Bag has the triple-zip Free-Flow zipper system for unmatched ventilation, yet remains light and packable due to its feather-light 10 denier nylon liner and shell and its 950+ fill power down insulation – the highest-lofting down Sea to Summit has ever used.

The Spark Pro is joined by the brand new Ascent / Women’s Ascent Down Sleeping Bags as possibly the most versatile technical sleeping bags out there. The 2024 Ascent has a redesigned technical hood, which has been sized to fit a Regular Aeros Pillow (an often overlooked part of a sleep system), and has been upgraded to 750+ goose down insulation to keep you warm in colder temperatures. As the mercury rises, the Free-Flow zipper system allows you to increase ventilation sequentially until the sleeping bag is opened completely flat as a quilt. Used with an appropriate liner – say the new Reactor or Breeze – an Ascent will provide true comfort across three seasons. And, of course, the Ascent / Women’s Ascent can be zipped together to form a cozy sleep environment for two.

Such versatility is not restricted to the more technical sleeping bags. The 2024 650+ fill power Trek Down Sleeping Bag and Women’s Trek Down Sleeping Bag are aimed more at the recreational user – yet they have also been upgraded for 2024 to include the full triple-zip Free-Flow zipper system. Open the zippers as you need more ventilation – you can even ‘wear’ the Trek at camp. The broader cut of the Trek (which has made it such a popular option) remains; Campers and travellers who are weary of being squeezed into excessively narrow mummy bags, or wary of cold spots in unsophisticated rectangular bags can take comfort in the Trek’s roomy yet thermally efficient shape. Add an Aeros Pillow to the hood, or zip the Unisex Trek to the Women’s Trek for a snug sleeping space for two. However you configure your Trek, you will enjoy enhanced comfort wherever your travels take you.

Free Flow zip system

Ventilation is often overlooked in sleeping bags, as end-users are encouraged to focus only on the coldest temperature they will sleep at when purchasing a bag. As a result, many bags are one-trick-ponies: good in one season, less good in a second season, and something of a compromise in a third season. In contrast, the zippers of a Free Flow sleeping bag can be opened as needed to allow ventilation, right up to the point where a bag can be opened flat as a quilt. You can keep the shoulder snaps closed, then open the side zippers to reach your arms out. This allows you to sit in your tent, enjoying coffee or reading, all while remaining snug in your sleeping bag. Additionally, by opening the footbox zipper, you can even 'wear' the sleeping bag, perhaps even for a quick trip outside.

All unisex/Women’s Free-Flow sleeping bags can be zipped together to form a bag for two, regardless of bag length.

Premium and sustainable materials

Our commitment to quality and sustainability continues to strengthen each year. In 2024, our updated down sleeping bags and quilts have been crafted using RDS Down. The Responsible Down Standard (RDS) describes and (independently) certifies animal welfare practices in down and feather production and tracks the certified [down and feathers/material(s) from farm to final product.

The down is treated with our Ultra-Dry Down hydrophobic treatment, which is free of PFCs and PFAS.

Recycled nylon and polyester shell and lining materials are used wherever possible. The DWR (durable, water-repellent) finishes used on all 2024 sleeping bags are also PFC and PFAS-free.

All shell and liner materials and down insulation used are bluesign approved.

Engineered for Women

Sea to Summit is 100% committed to the 51% of the population often overlooked when it comes to outdoor gear. Our Women’s Specific sleeping bags are the perfect example of this: they are built differently from the unisex versions from the ground up. The shape is narrower in the shoulders (as a woman, why should you carry extra weight that does nothing for you?), and wider between the hips and the knees. This thermally efficient design allows a woman sleeper to sleep on her side, on her stomach or in a ‘figure four’ position without flattening the insulation and creating cold spots. The down is filled into the individual chambers using different body mapping than the Unisex sleeping bags, to provide women extra warmth where they need it. And as of 2024, you will find temperature and price parity between equivalent Unisex and Women’s Specific models.

Enhancing the sleep system concept

There is a separate post covering the fabrics and performance of the 2024 sleeping bag liners, but their function has been upgraded for 2024, too. Sea to Summit’s new liner range includes performance models that have openings built into the shoulders and drawstring openings in the foot section. These liners, therefore, harmonize perfectly with the Free-Flow sleeping bags to form the most comfortable, most livable sleep systems yet.

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