Two bags in one

Spitsbergen X-Trem is our warmest sleeping bag - ever


    • Weight: 3.31 kg
    • T-Lim: -45°C
    • Person length/width: 195/85 cm
    • Volume compressed: 37x29 cm (24L)


    Helsport has decades of experience designing equipment for polar exploration. Our tents have been used in some of the most severe environments on earth and we needed sleeping bags to match. In the Spitsbergen we have created a unique design with feedback from our most experienced ambassadors blended with our own experience and incorporating a new level of thermal efficiency from the fit and fill technology used in our Rago range.

    Every aspect of sleeping in comfort in extreme cold has been considered with the design of this twin-bag system.

    The Spitsbergen is a lot of sleeping bag! It incorporates the warmth and comfort of goose down, the cold-weather performance of synthetic fill, an extra thermal boost with shingle construction, high-quality Pertex fabrics throughout, an innovative zipper solution for maximum flexibility and our comfortable and efficient fit system. It follows the Helsport “Long” fit including extra width for changing or adding clothes whilst inside the bag and reducing the chance of cold spots forming at pressure points.

    Inner:  The inner bag is down-filled with extra added to the foot baffles, a close-fitting hood with extra fill and a sculpted internal heat collar that sits naturally and comfortably over the shoulders.

    All the zips are kept as short as possible and feature generous insulated flaps.

    There is an extra zip for the arm on the right-hand side at elbow height, covered by a soft outer flap to prevent snagging. The main zip on the left has three sliders that can be reconfigured to make an opening for an arm as well. This double-zip design means you can sit up wearing the inner bag like a jacket and staying toasty-warm, but with both arms outside the bag for eating, reading, or just getting ready for sleep. Any items you need to access quickly can be kept in the generous chest pocket inside.

    The hood and internal collar both have drawcords so the inner bag can be closed down in very cold conditions or opened up if needed. It is also easy to regulate your temperature using the double zips.

    The chest baffles have been specially-designed around the double zips using two long vertical baffles at the sides and short horizontal baffles over the chest, which all work to keep the down in place, maximising loft and warmth.

    The Spitsbergen inner bag uses the same premium-quality Pertex fabrics as our Rago Xtrem series and is filled with 750 FP 90/10 goose down.

    Person length/width: 195/85 cm Weight: 1,51 kg EN 13537 T-Lim: -25  Insulation: 90/10 goose down, 750 FP Weight insulation: 861 g

    Outer: The outer bag is quite a different design from the inner, with a short central zip and synthetic fill. The central zip means the inner and outer bag zips are offset from each other to minimise heat loss, and avoid confusion in the night if you need to get up. The zip is protected by an insulated flap which folds over the top to prevent freezing from your breath.

    We used synthetic fill for the outer bag due to a crucial but little-known fact about sleeping in cold environments. We all lose moisture through our skin when we sleep. If it is cold enough, that moisture can freeze inside the bag fill before it’s had a chance to escape. Over time this can build up as ice and be a real problem on long expeditions. With the Spitsbergen, the ice will still form inside the outer bag fill, but being synthetic will not affect the insulating properties as much, and can dry much faster than down.

    To further boost the warmth, we layered the fill in a “shingle” type construction over the top. Shingle construction uses overlapping pieces of fibre blanket instead of a single sheet. This allows for greater freedom of movement and also traps additional warm air between the layers. We have found in EN testing that shingle construction can be up to 15% warmer than a simple blanket fill design. We have selected a recycled synthetic fill that nonetheless meets our demanding standards of thermal efficiency.

    The overall shape of the bag is designed to fit over the inner without compressing the fill and the hood is shaped so it can easily be pulled up over the inner hood for warmth or laid flat and filled with clothes to use as a pillow.

    We experimented with joining the inner and outer bags together but found it was too easy for the bags to twist up and become tangled inside each other. When the inner bag is free, sleeping is much less restricted.

    The outer bag uses the same comfortable high-quality Pertex liner fabric as the inner bag, but a tougher Pertex shell fabric that is treated inside with an additional 1000mm water-resistant breathable coating. All of the fabrics have C6 WR treatment.

    The outer bag also features a generous internal zipped pocket for valuables with an easy-to-use vertical zip.

    Person length/width: 200/90 cm Weight: 1,56 kg EN 13537 T-Lim: -11  Insulation: Thermolite® T3 Ecomade Weight insulation: 861 g

    Designer Tips:  When you get into the Spitsbergen, close the outer bag zip first. Then it’s easy to zip up the inner bag once you have settled down.If you get too warm during the night, use the inner bag zips to regulate your temperature. Because the Spitsbergen uses the same fit as our Rago Long fit, it is easy to use the outer bag separately to boost our other sleeping bags.

    • Zip:Left
    • Zip length (cm):120
    • Fill Material:90/10 Goose down RDS 750 FP, Thermolite T3 Ecomade
    • Fill weight (g):861
    • Net weight (kg):3.43
    • T-Comf:-32
    • T-Lim:-45
    • T-Ext:-70
    • Sleeping bag person length (cm):195
    • Sleeping bag person width (cm):85
    • Gender:Unisex