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Sea to Summit Trek Down Sleeping Bag -18°C

Size: Regular

The Sea to Summit Trek -18°C down sleeping bag is a 4-season bag that offers both the snugness of a tapered rectangular mummy shape and the flexibility of a dual-zip ventilation system, making it perfect for any journey. The innovative Free Flow Zip System includes a full-length side zip and an additional foot box zip, allowing for customizable ventilation options and the ability to lay the Trek flat like a duvet. The sleeping bag allows you to keep your arms free while staying warm, making it convenient for activities such as cooking during the day.

Its high-quality down filling ensures warmth and comfort on colder nights. Filled with 650+ Fill Power, RDS-certified, Duck Down with Ultra Dry Down treatment for improved water resistance in damp conditions.

The Trek's cocoon-like shape provides ample space for movement while sleeping, no matter your position. This ultralight and compact down sleeping bag is perfect for trekking, backpacking, travelling, or camping adventures. You can also form a snug double sleeping bag by zipping it onto any women's Sea to Summit sleeping bag.

Pair up your Sea to Summit sleeping bag with a compatible liner for the ultimate sleep system. Sleeping Bag Liners

More Help? For further assistance on choosing your down sleeping bag, we have an article explaining fill power, the pros and cons of down over synthetic insulation and more info on caring for your bag available to view here: A Guide to Down Sleeping Bags.


  • Duck Down with UltraDry Down treatment for improved water resistance in damp conditions.
  • Insulation: 650+ FILL Power, RDScertified, Duck Down with Ultra Dry Down treatment for improved water resistance in damp conditions.
  • Recycled polyester offers durability and comfort for lightweight adventures in a range of climates and conditions.
  • Includes lightweight Ultra-Sil compression bag and storage cell.
  • The Free Flow Zip System offers temperature regulation and multiple sleeping bag configurations for added freedom in the outdoors.
  • The Semi Rectangular Fit features a spacious design for added comfort and room that is best suited to car camping and shorter adventures.
  • Hood: Generous fitted hood with two soft touch adjustments. Fits a Sea to Summit regular pillow.
  • Draft Tube: Single, synthetic-filled, draft tube along the top of all
  • Internal pocket for phone / GPS / valuables.
  • Full-length YKK® #5 main side zip and foot box zip provide superior ventilation and allow the bag to be used as a comforter.
  • Can be paired up Pairs with women's Sea to Summit bags.
  • Pillow integration: Sea to Summit Regular Pillow fits inside hood.
  • Colar: Trek -1C/30F & -9C/15F Fitted front draft collar: scalloped over the neck and oversized at the shoulders. Trek -18C/0F Double draft collars: fitted front collar and tubular back collar.
  • Baffle Construction: Vertical chest baffles, horizontal baffles lower half and base, box wall baffle construction throughout.
  • QuiltLock: Every Sea to Summit sleeping back features the QuiltLock system that uses the snap locks located at the shoulder and foot end of Sea to Summit sleeping bags plus the quilt footbox / quilt straps to secure a quilt to the sleeping bag. This adds thermal performance and versatility to your sleep system: your integrated Sea to Summit quilt now works for ultralight summer adventures and turns your three-season bag into a four-season sleep system.


    • Maximum User Height:  Regular: 185cm /  - Long: 198 cm
    • Comfort Temperature: -11°C
    • Comfort Temperature limit:  -18°C
    • Shoulder width:  Regular: 158 cm / Long: 168 cm
    • Waist With: Regular: 149 cm / Long: 159 cm
    • Foot box width:  Regular: 119 cm / Long: 129 cm
    • Insulated collar: Yes
    • Shell Fabric: Recycled 20-Denier Polyester shell and lining.
    • Filling:  Duck Down
    • Fill power: 650+
    • Weight: Regular: 1895g / Long: 2098g
    • Fill Weight: Regular: 1000g / Long: 1163g
    • Compression Size: 26L
    • Zip: Left

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