Sea to Summit
Sea to Summit Spark 7 °C down sleeping bag (Regular)
Best use
- Made for
- Backpacking and wild camping
- Also works for
- Bikepacking
- 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.
- Bikepacking: Small enough for bike bags: packs to 2 litres
- Winter mountain: Comfort rating 11 °C: too cold for winter nights
From the maker's stated use and the published specs.
- Summer wild camp: 7/10 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. Below this trip's minimum: needs warmth 9+ (comfort -5 °C or colder).
- Weight: 10/10 How much it adds to your pack, compared with the whole market.
Comfort 11 °C, limit 7 °C (ISO 23537).
Summer wild camps and warm lowland nights above about 11 °C, when weight and bulk matter most
- Zip
- Half
- Comfort
- 11 °C
- Limit
- 7 °C
- Fill
- 850 fill down
- Weight
- 363 g (Regular)
Packed size 2 L, 23 x 12.5 x 9 cm Compare with a 2-litre bottle
Shorter than a 2-litre bottle and a bit wider than one. Drawn to scale.
Where to buy
Alpinetrek £268.80 In stock. Free delivery.
View at shop: AlpinetrekUltralight Outdoor Gear £254.99 Out of stock. Regular out of stock on 2 Nov 2026 (the Long is in stock at £279.99). This shop shows an RRP of £299.99.
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 2/10How cold a night you can sleep comfortably through. 2: A weak point.
ISO comfort 11 °C (lower limit 7 °C) is above 10 °C, so it sits in the 1 band. A summer bag, sold by the maker as an ultralight warm-weather bag. The maker's figure, not re-tested.
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 10/10How much it adds to your pack. 10: The best you can buy for this.
363 g (Regular, without sacks) is under 700 g, so band 5.
Packed size
From maker's figures 10/10How much room it takes in your rucksack. 10: The best you can buy for this.
Maker states a 2 L compressed volume, under 4 L, so band 5. Its stuffed packed size of 23 x 12.5 x 9 cm is about 2.6 L as a box, in the same band.
What reviewers say (out of 10)
Ratings marked * are from reviews and are not part of the trip score. They are reviewers' scores, not our own measurements. How we score
Comfort to sleep in*
Estimate: only 2 reviews about comfort to sleep in (fewer than the 3 we need, so never above 8) 8/10How comfy the shape, hood and fabric feel; not the temperature rating.
2 reviews on comfort to sleep in, e.g. "The hood on the Spark is good and features a full collar the whole way around".
Zip*
Estimate: only 2 reviews about zip (fewer than the 3 we need, so never above 8) 8/10How smoothly the zip runs without snagging.
2 reviews on zip, e.g. "I tried my best to destroy the zip and tried to snag it on the internal draft collar. All attempts failed.".
In short
Good for
- Summer wild camps and warm lowland nights above about 11 °C, when weight and bulk matter most
- Adding to a warmer layer system: it packs to 2 L and weighs 363 g
Strengths
- Very light for a down bag, 363 g, and packs to 2 L
- 850 fill goose down with an Ultra-Dry treatment, a 10D shell and a hood and footbox in water-repellent fabric against tent condensation
- Half-length zip with a zip plow, a draft collar and a fitted hood
- The cheapest and lightest bag in the Spark range
Weaknesses
- ISO comfort 11 °C and limit 7 °C: too cold for most UK nights outside summer, even with layers
- Thin 10D fabric and sewn-through baffles keep it light but leave it less tough than a bag with a heavier shell
- Narrow mummy cut with little room to move
- We found no independent review of the current Spark 7 °C, so damp performance, comfort and durability are estimates, not reviewed scores
Sources
We haven't tested this ourselves. Every score comes from these specs, tests and reviews.
ShowHide sources (5)
- Sea to Summit: Spark Down Sleeping Bag, 7 °C Regular specifications (maker's page: ISO limit and comfort, weight, compressed volume, packed size)
- Ultralight Outdoor Gear: Sea to Summit Spark 7C Down Sleeping Bag (UK shop page: weight, comfort, fill)
- Sea to Summit UK: Spark Ultralight Sleeping Bag (list price £300 for 7 °C Regular)
- Bike Hike Safari: Sea to Summit Spark Sleeping Bag Review (whole Spark range tested, 45F/7°C 363 g listed first)
- The Trek: Sea to Summit Spark 45 Sleeping Bag Review (Regular, 45F)