Sea to Summit
Sea to Summit Hamelin Synthetic -1 °C Sleeping Bag (Regular)
Best use
- Made for
- Backpacking and wild camping, Car and festival
- Not for
- Winter mountain
Why these labels
- Backpacking and wild camping: The maker states this use, and the published specs do not rule it out.
- Car and festival: The maker states this use, and the published specs do not rule it out.
- 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).
Budget summer and mild shoulder-season wild camps and bivvies in the damp UK, where synthetic fill copes with condensation
- Zip side
- Both
- Comfort
- 3 °C
- Limit
- -1 °C
- Fill
- synthetic
- Weight
- 1.12 kg (Regular)
- Packed
- 8.4 L
Where to buy
Sea to Summit £170 In stock. Free delivery. Free delivery over £75.
View at shop: Sea to SummitAbsolute Snow £169.95 Out of stock. Shop page says currently unavailable.
View at shop: Absolute SnowUltralight Outdoor Gear £144.99 Out of stock. Regular out of stock on 2 Nov 2026 (the Long is in stock at £149.99).
View at shop: Ultralight Outdoor GearPrices checked 2 Nov 2026 to 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.
Maker's ISO comfort rating is 3 °C (lower limit -1 °C), in the 0.1 to 5 °C band. The -1 in the name is the lower limit.
Room inside
Estimate from maker's specs: bag shape (fewer than 3 reviews about room) 3/10How much room to move, bend your knees and sleep on your side. Roomier is comfier. 3: Below average. Fine for some trips, not others.
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.
1,124 g (Regular, maker's table) sits in the 1,000-1,299 g band. Ultralight Outdoor Gear lists 1,189 g.
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's compressed volume is 8.4 L, in the 6-8.9 L band. Live for the Outdoors found it still feels big and bulky in its stuff sack.
In short
Good for
- Budget summer and mild shoulder-season wild camps and bivvies in the damp UK, where synthetic fill copes with condensation
- Anyone who wants an easy-care bag that dries quickly
- Side sleepers and restless sleepers who find a tight mummy bag restrictive
Strengths
- Synthetic fill (100% recycled) keeps working when damp and is easy to wash
- Relaxed mummy cut with room at the footbox, knees and shoulders
- Full-length side zip plus half-length zip on the other side give good venting and let it open like a quilt
- ISO 23537 ratings of 3 °C comfort and -1 °C lower limit from a lab test
Weaknesses
- Heavy for the warmth at 1,124 g, and bulky at 8.4 L compressed
- Only a 3 °C comfort rating, so it suits summer and mild shoulder-season nights in the UK, not frosty spring or autumn ones
- Larger than down equivalents: Live for the Outdoors says you need a 60 L or bigger rucksack to carry it with your other gear
- Only one independent review of this exact bag found, so damp, comfort and durability are estimates, not reviewed scores
Sources
We haven't tested this ourselves. Every score comes from these specs, tests and reviews.