Sea to Summit Spark Ultralight Down Sleeping Bag — 0°F (Regular)

Meet the Spark: ultralight warmth for adventurous nights

The Sea to Summit Spark 0-Degree Ultralight Down Sleeping Bag pairs serious warmth with a featherweight profile, ideal for backpackers, bikepackers, and touring enthusiasts who crave compact packability without sacrificing comfort. With a 0°F (-18°C) rating, it’s designed for cool-to-cold nights where every gram counts. The bag uses high-loft 850+ fill power down that is Responsible Down Standard certified and treated with a proprietary non-PFC Ultra-Dry Down finish to help loft rebound and maintain performance when humidity or dampness challenge the material.

Designed for a natural sleeping position, the contoured mummy shape and full box baffles work together to trap warmth while maximizing loft. The ultralight 10D nylon shell offers water resistance via a PFC-free DWR, and the 10D liner enhances breathability for all-night comfort. A snag-free YKK #5 zipper ensures smooth operation, so you can adjust to the night’s temperature without hassle. The Spark 0-Degree is available in Regular and Long sizes, and it arrives with an Ultra-Sil compression sack and a storage cube to simplify packing and care.

Key design features at a glance

• 0°F (-18°C) rating designed for 3-season backpacking, bike packing, and touring
• 850+ fill power down, Responsible Down Standard certified, plus non-PFC Ultra-Dry down treatment for better loft retention
• Ultralight 10D shell with PFC-free DWR; breathable 10D liner for all-night comfort
• Contoured mummy shape with full box baffles to maximize warmth and natural sleeping position
• YKK #5 zipper for reliable, snag-free operation
• Includes Ultra-Sil compression sack and storage cube; Sea to Summit lifetime guarantee

In the field: what to expect

• Lightweight and compact packing makes it a strong option for ultralight setups and fast-paced trips
• Moisture resistance and loft retention help maintain warmth in variable conditions
• Breathable liner and efficient shell keep you comfortable through long nights outdoors
• Durability and a lifetime guarantee support long-term use in rugged environments

Note: temperature ratings reflect standard testing and do not guarantee specific outcomes for every sleeper. Real-world warmth depends on your layering, sleep system, and local conditions. The Spark bag is designed to offer strong potential warmth and comfort for a variety of adventures.