Designed for ultralight adventures in any climate, the Spark Down Sleeping Bag balances weight, warmth, and packability. It is filled with RDS-certified 850+ fillpower goose down treated with PFAS-free Ultra-Dry Down to resist moisture and maintain loft. The 10D bluesign®-approved liner fabric is soft and breathable, while the 10D shell features a PFAS-free DWR with reinforced, water-resistant hood and footbox panels to protect against condensation.

An ergonomic mummy fit, draft tubes, and a technical hood help seal in warmth without unnecessary bulk. Full-length zip versions can be paired with Women’s Spark bags, and the QuiltLock system allows you to attach a compatible Sea to Summit quilt for extra layering when conditions drop.

Features

• RDS-certified 850+ fillpower goose down with PFAS-free Ultra-Dry Down for lasting loft and moisture resistance
• Ultralight 10D bluesign®-approved nylon liner and 10D shell with PFAS-free DWR, plus reinforced water-resistant hood and footbox panels
• Ergonomic mummy fit with a technical hood, anatomical footbox, and generous draft tubes to seal in warmth without excess weight
• Updated YKK #5 zipper with snag-free plow design for smoother operation and improved durability
• QuiltLock system allows compatible Sea to Summit quilts to attach over the bag for extra insulation in colder conditions
• Baffle construction tailored to each model: sewn-through (7°C), hybrid box/stitched (-1°C), or full box baffles for maximum warmth (-9°C, -18°C)
• Zip options vary by model: half-length for lighter packs (7°C, -1°C) or full-length side zips for versatility (-9°C, -18°C)
• Includes compression sack, large mesh storage bag, and certified down test certificate for quality assurance
• Backed by the Sea to Summit Lifetime Guarantee

Performance

Weight
Among the lightest sleeping bags in its class, starting at just 363g for the 7°C model and staying under 1.2kg even in the -18°C version.

Packability
Premium 850+ down compresses to a tiny size. Each model includes a compression sack for on-trail storage and a mesh storage bag for at-home loft recovery.

Climate
Temperature ratings span from 7°C down to -18°C, making the Spark suitable for warm-weather hikes through to high-altitude or sub-zero expeditions.

Tech specs

• Best Use
  Ultralight backpacking, alpine missions, and fast-and-light adventures where every gram counts.

Comes With
40D recycled bluesign®-approved nylon compression sack, large mesh storage bag for at-home loft recovery, and a certified down test certificate.

Insulation
RDS-certified 850+ fillpower goose down with PFAS-free Ultra-Dry Down treatment for reliable loft and moisture resistance.

Shape
Streamlined mummy fit with an anatomical footbox and technical hood.

Zip Options
Durable YKK #5 zipper with snag-free plow. Half-length zips on 7°C and -1°C models for weight savings; full-length side zips on -9°C and -18°C models for versatility.