The Sea to Summit Ascent 30 is a lightweight down sleeping bag with impressive quilt-like venting features. Given its temperature rating, it is suitable for much warmer temperatures than you’d expect. It has thermally efficient box baffling and packs up surprisingly small. Its relaxed, spacious fit belies the fact that it’s a mummy sleeping bag.
- Gender: Men’s (Women’s model available)
- Type: Relaxed Mummy
- Insulation: 750 fill power water-resistant down
- Weight: 1 lb 11.6 oz
- Fits to: 6′ 2″
- Shoulder/Hip/Footbox: 62.2″/57.5″/46.9″
- Zippers: 3 (YKK#5)
- Foot box Vent: Yes
- Temperature Rating: 30F for cold sleeping, 38F for warmer sleepers
- Compressed volume: 5.5 liters
- Pros: Great venting for warmer temperatures, box baffling, relaxed hood
- Cons: Mummy hood is giant, better for camping than backpacking
Down sleeping bags are not inexpensive, so if you can only afford to buy one sleeping bag or quilt, you want one that is going to perform across the widest temperature range. That’s the value proposition that the Sea-to-Summit Ascent 30 delivers on with a ventable foot box and dual side zippers that let you fold down the top of the sleeping bag like a blanket.
The Ascent 30 has a relaxed mummy shape that strikes a good balance between thermal efficiency and space to move around it, making this a good bag for side sleepers like myself. The hood is large enough that it can hold a pillow or you can just fold it backward and rest your head on it, using the bag without a hood, which is nice in warmer weather.
Insulated with 750-fill power down, the Ascent 30 has vertical baffles over the chest and horizontal baffles over the legs to prevent down shift and ensure the down remains optimally distributed for warmth. The insulation is structured in boxed baffles for maximum warmth and to prevent warm-air leaks from the needle holes that occur with stitched-through construction.
The Ascent 30 has three zippers, two on the sides and one in the footbox. The right zipper is half-length while the right zipper is full-length, so you can open the bag wide in warmer weather or just fold down the upper half, as illustrated above. The zipper and venting increase the bag’s temperature range quite significantly: I’ve slept in it comfortably into the upper 70’s (F) by opening up the side zippers and using it like a quilt, adjusting it during the night as my body cooled and temperatures dropped. It’s a lot like sleeping in your bed at home!
Both of the side zippers have an anti-snag head and do a good job of preventing snags on the shell fabric. There is a snap at the top of each zipper, on the sides of the hood, so you can stick your arms out the sides and “wear the bag like a hooded jacket” if you want, which is good if you like to sit up to make coffee in your tent in the morning without getting chilled. The footbox also has a zippered opening for venting if you’re too warm at night, although its zipper does not have the anti-snag head or really need one because it is so short.
The hood is enormous enough that you can put a pillow inside and still snag the hood around your head. It has an easy-to-grasp adjuster so you can cinch the hood around your face. When it’s too warm to use, you can fold the hood under the bag and use the Ascent as a hoodless sleeping bag, which is rather nice. Unfortunately, you can’t run the draft collar around your neck and snap it closed like a quilt since it’s not long enough, although that would be a great feature. Perhaps a future version will have that.
The down in the Ascent has been enhanced by the Ultra-Dry non-PFC water-repellent treatment. While it doesn’t make the down completely waterproof, it helps reduce the negative effects of dampness so that it retains over 60% more loft, absorbs 30% less moisture, and dries out 60% faster than untreated down (according to the manufacturer). Net net, the down in your bag will keep you warmer in cold and humid conditions and dry faster, which is particularly advantageous on multi-day trips. However, the downside of “waterproof” down is that the chemical waterproof coating does wash out if you wash the sleeping bag often and renders the down less water-resistant than if it was untreated.
The Ascent 30 comes with a convenient storage sack and a compression sack. The storage stack should be used at home to extend the down’s lifetime and let it loft naturally between trips. The compression sack shrinks the sleeping bag to 5.5 liters, so it takes up much less space inside your backpack. It’s pretty impressive just how small the Ascent 30 packs up when compressed, especially when compared to a similarly rated synthetic insulated sleeping bag.
Recommendation
The Sea-to-Summit Ascent 30 is an innovative down sleeping bag that emphasizes comfort and versatility over ultralight weight. If you’re looking for a warm and roomy sleeping bag that can be used across a wide range of temperatures, the unique zipper system provides unprecedented thermal flexibility. While not for everyone, the Ascent 30 is a great find if you want one bag that can do everything without compromising on fit or features.
Disclosure: Sea-to-Summit donated a sleeping bag for review.
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