We’ve tested a lot of kit from Aussie brand Sea to Summit over the years, and invariably we’ve been impressed. The Spark SPIII is no exception. It’s an extremely light and packable premium down sleeping bag that offers superb warmth for weight, without the uncompromising fit of most ultralight bags.
It’s stuffed with 850 fill power goose down with a hydrophobic treatment for improved performance in damp conditions (the traditional drawback of down-insulated sleeping bags). There’s plenty of it too, with an impressive 430g fill weight. This gives a comfort rating of -2°C and a lower limit of -8°C. Yet the bag weighs just 665g in total.
To achieve this, the shell and lining fabrics are superlight 10D nylon. Box-wall baffle construction throughout maximises down loft and reduces potential cold spots. Yet unlike many highly tapered ultralight bags, which often feel restrictive, the Spark’s added wriggle room makes it pleasantly accommodating. Other features are fairly limited, but you still get a long two-way zip for good ventilation and an easy-cinch hood.
In truth, the Spark SPIII is being retired in 2024, as Sea to Summit launches a fresh suite of sleeping bag models. But it’s still widely available, and remains a very comfortable bag that’s become one of our go-to 3-season sleeping bags for wild camps and multi-day backpacking trips from early spring through to late autumn, and it gets our Gear of the Year 2024 award.
Gear of the year 2024 winner
www.tiso.com
Pros
- More internal room compared to rivals
- Super lightweight
- Excellent warmth-to-weight ratio
Cons
- Lightweight fabrics are a little delicate
| Sizes | Regular (183cm), Long (198cm) |
| Packed size | 35 x 15cm |
| Weight | 665 (reg), 745g (long) |
| Insulation | RDS-certified 850-fill goose down w/ UltraDry treatment |
| Materials | 10D nylon shell and lining |
| Temperature rating | Comfort -2°C | Limit -8°C |
Why the Sea to Summit Spark SPIII won Gear of the Year 2024
Comfort
What we like most about this bag compared to other lightweight sleeping bags is its superior fit – unlike a lot of tapered mummy styles, which can make you feel like you’re sleeping in a straitjacket, this has a slightly more forgiving cut, resulting in increased comfort. It’s still thermally efficient without being too close or restrictive.
Awesome warmth-to-weight ratio
The use of premium 850 fill power down ensures this delivers superb warmth to weight. That’s vital if you’re aiming to minimise your trail weight on a long-distance walk, or if you just want to pack light for your next wild camp. Yet this is a bag that is still genuinely warm enough for sub-zero conditions.
Compressible and packable
As well as the high-quality down fill, this bag’s superlight performance fabrics mean it compresses very well. Of course, the thin fabrics mean you shouldn’t treat this bag too roughly – not easy when you’re trying to wrestle it back into its minuscule stuffsack. But that does ensure the packed size is impressively tiny for a 3-season bag. Just give it plenty of time to loft before you hit the hay.
How we tested
Our Gear of the Year award winners are, what we consider, the best products in their category that we've tested in the previous 12 months.
The products have all been used in tough real world conditions by members of our rigorous and experienced team.