Sea to Summit
Sea to Summit Trek -1 °C down sleeping bag (Regular)
Best use
- Made for
- Car and festival
- Also works for
- Backpacking and wild camping
- Not for
- Winter mountain
Why these labels
- Car and festival: The maker states this use, and the published specs do not rule it out.
- Backpacking and wild camping: Light to carry: 1.1 kg
- Winter mountain: Comfort rating 3 °C: too cold for winter nights
From the maker's stated use and the published specs.
- Summer wild camp: 5/10 UK, roughly May to September, nights above about 8 °C, sheltered pitches.
- Three-season hills: 4/10 UK hills in spring and autumn. Wind, rain, and nights near freezing. Capped at 4: needs warmth 7+ (comfort 0 °C or colder).
- Winter camp: 4/10 UK winter or high ground. Below freezing, strong wind, possibly snow. Capped at 4: needs warmth 9+ (comfort -5 °C or colder).
- Weight: 6/10 How much it adds to your pack, compared with the whole market.
Comfort 3 °C, limit -1 °C (ISO 23537).
Cheaper three-season camping with a roomy cut, on trips where pack weight is not the first concern
- Comfort
- 3 °C
- Limit
- -1 °C
- Fill
- 650 fill down
- Weight
- 1.12 kg (Regular)
Packed size 8.2 L, 41 x 22.5 x 15.5 cm Compare with a 2-litre bottle
A bit longer than a 2-litre bottle and about twice as wide. Drawn to scale.
Where to buy
Ultralight Outdoor Gear £279.99 In stock. Free delivery.
View at shop: Ultralight Outdoor GearAlpinetrek £210.67 Out of stock.
View at shop: AlpinetrekPrices checked 8 Nov 2026 on each shop's own page; shops can change them. We earn no commission on these links; shops are listed by price. More
Our ratings (out of 10)
1 to 10, compared with the whole market. Each says what it's based on. How we score
Warmth
From maker's figures 5/10How cold a night you can sleep comfortably through. 5: Does the job. Average for wild-camping gear.
Sea to Summit lists ISO comfort 3 °C (lower limit -1 °C), which sits in the 0.1 to 5 °C band. One UK shop labels the figures EN 13537 with a limit of -2 °C; we use the maker's own page. The maker's figure, not re-tested.
Room inside
Estimate from maker's specs: bag shape (fewer than 3 reviews about room) 5/10How much room to move, bend your knees and sleep on your side. Roomier is comfier. 5: Does the job. Average for wild-camping gear.
No review we found says how roomy it is, so this is an estimate from the bag shape.
Weight
From maker's figures 6/10How much it adds to your pack. 6: A bit better than average.
1,119 g (Regular, without sacks) sits in the 1,000-1,299 g band. The UK shop lists 1,108 g, in the same band.
Packed size
From maker's figures 5/10How much room it takes in your rucksack. 5: Does the job. Average for wild-camping gear.
Maker states an 8.2 L compressed volume, so we use that (6-8.9 L band). Its stuffed packed size of 41 x 22.5 x 15.5 cm works out larger as a box (about 14.3 L), and the UK shop lists 13 L, which would be the 13 L+ band, so treat it as the top end of its band.
In short
Good for
- Cheaper three-season camping with a roomy cut, on trips where pack weight is not the first concern
- Campers who like to vent: the full-length zip opens right out like a quilt
Strengths
- Roomy, tapered rectangular cut with space for side sleepers, in a 1,119 g down bag
- Free Flow zips (full-length main zip, half-length second zip and a foot zip) allow plenty of ventilation
- Down is treated with a PFAS-free Ultra-Dry Down coating for damper conditions
- Single draft tube along the zips, and a fitted hood that takes a pillow
Weaknesses
- ISO comfort is only 3 °C, so cold sleepers need a warmer bag or layers for UK spring and autumn nights near freezing
- Not light or compact: 650 fill down at 1,119 g and 8.2 L (the UK shop quotes 13 L), against 880 g for the Nemo Disco 30
- The roomy cut leaves more air to warm up
- We found no independent review of this exact bag, so damp performance, comfort and durability are estimates, not reviewed scores
- UK shops and the maker disagree on some figures (limit -1 °C or -2 °C, packed volume), so check the label before you buy
Sources
We haven't tested this ourselves. Every score comes from these specs, tests and reviews.
ShowHide sources (3)
- Sea to Summit: Trek Down Sleeping Bag, -1 °C Regular specifications (maker's page: ISO limit and comfort, weight, compressed volume, packed size)
- Ultralight Outdoor Gear: Sea to Summit Trek -1C Down Sleeping Bag (UK shop page: weight, comfort, fill)
- Sea to Summit UK: Trek Down Sleeping Bag (list price £325 for -1 °C Regular)