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Extra consideration is often required when choosing a winter kit. Especially kit you wish to spend a night in below zero conditions with potentially a long walk away from the nearest road. How much each piece of gear weighs will be a factor but more importantly, it needs to be up to the job. A sleep mat is a key item as it is the main barrier against the frozen ground, to help provide a warm and comfortable night’s sleep.

The Nemo Tensor Extreme with an R rating of 8.5 sounds bang up to the task and also is very small in size and weight ticking all the boxes. Even the wide version we received only weighs in at 624 grams, making for a perfect mat for year-round use let alone simply for winter. Don’t be fooled into thinking the small pack size won’t deliver in performance, the Tensor Extreme excelled above our expectations. This is a very warm mat indeed.

We certainly gave it some real-life testing including many winter bivvy camps (our preferred way to travel in winter), a night in a snowhole, and an early spring season low-level camp, ranging between temperatures of -10 to +3 degrees. Even in the coldest of temperatures we only needed to take a relatively modest winter rated sleeping bag (Gruezi Bag Ice Cold -5 Comfort) and we could never feel the cold below seeping into our bag.

The large rectangular shape of 183 cm x 64 cm makes for a very wide and long mat indeed, more than enough space, which makes a big difference in winter, keeping unwanted arms from coming off the mat and in contact with the cold ground. There is maybe one slight issue which is the Wide Tensor Extreme will only just about squeeze inside larger bivvy bags.

You would assume that the weight-to-warmth ratio would result in a lack of comfort and again it’s quite the opposite in use. The Apex baffle design is unlike much we have used previously and makes for a comfortable night’s sleep. Not quite as much loft as other winter graded mats but still a very nice place to lay off a night.

The success of the Tensor Extreme is what Nemo claims are “four sheets of Thermal Mirror Metallised Film suspended (not welded) throughout the mat; these layers reflect your body heat back towards you.” This results in a warm, comfortable, and importantly for many a quiet mat. One that doesn’t disturb your climbing partner throughout the night.

There are some sacrifices that we have noticed that need to be made to keep this mat as light and compact as possible. Most notably in the fabrics, the 40D nylon bottom, and 20D nylon upper is a bit on the light side compared to my usual choice. We did encounter one minor puncture which was quickly fixed, although it will be interesting to see how the durability with hold up after a couple of years of use.

The Vortex Pump Sac and Lay Low valve were a bit underwhelming compared to the precision applied to the rest of the design. The pump sac in particular is quite small in volume and would pop away from the mat when inflating. These we do have to say are very minor issues and ones which shouldn’t take away from how good a mat the Nemo Tensor Extreme performed over a very mixed winter season.

Our Verdict

The Nemo Tensor Extreme made a big impression with our guides. Not going to lie, it’s been hard to reach for another mat again after using this. We received the wide version, which although added a few extra grams than that of the regular, is well worth the investment for winter camping or simply to add a bit of extra comfort. Not to say that this is strictly a winter mat, at around 650 grams, and a respectfully small pack size, this could easily be used year-round cutting down on the size and weight of a summer sleeping bag. We often say to our clients that the most important factor to having a warm night’s sleep is to first pay attention to what’s in direct contact with the ground. With an R rating of 8.5, the Tensor Extreme is about as good as it gets currently. Our only niggles (in which there were very few) were with the pump sac and valve. Which overall shows how impressed we are with the Nemo Tensor Extreme.

Trek Scotland is a small family business based in the picturesque village of Tomintoul in the North East region of the Cairngorms National Park. They provide bespoke Mountain Guiding for Single Day Walks and Lightweight Multiday Trekking experiences, including wild camping, in the stunning Cairngorms wilderness and surrounding areas. Whether in the high mountains or lower valleys, their Multiday Treks are equipped with high quality, lightweight camping and trekking gear. They only work with small groups and, whatever your ability, pride themselves on designing your outdoor experience completely to your needs and with professional guidance and expertise. Adventure is waiting... Read more from Trek Scotland