Sea to Summit UltraLight Insulated Mat

Andi Stader reviews the Sea to Summit UltraLight Insulated Mat for Blister Gear Review
Sea to Summit UltraLight Insulated Mat

Sea to Summit – UltraLight Insulated Sleeping Mat

Inflated Size: 72” x 21.5” x 2”

Packed Size: 4”x 9”

Stated Weight: 440 grams (15.5 oz)

Outer Material: 40D ripstop nylon with Exkin Platinum reflective material

Inner Material: Independent air sprung cells with Thermolite insulation and TPU lamination to eliminate weld delamination with antimicrobial treatment

R-value: 3.3

MSRP: $129.95 (regular) – $149.95 (Large)

Reviewer: 5’8”, 123 lbs.

Days Tested: 30+

Test Locations: The Gore mountain range, Rocky Mountain National Park, CO



When I first got into mountaineering and realized the importance of minimizing the size and weight of every item in my pack, I got myself an Alps Mountaineering Nimbus Air Sleeping Pad and used it for a couple of seasons. I found that I still slept pretty cold, but I was happy with the size (4”x11” packed) and the weight (1lb 4oz).

However, during Outward Bound instructor training in the Sangres this past May, I found that when I slept on my side, my hip would compress the mat, contact the snow, and I would freeze. Despite the 3.5” of height the Nimbus has, it only has a “R-value” of 1.

R-value is an indicator of a thermal material’s ability (in our case, a sleeping pad’s ability) to resist heat transfer from the user to the ground. So roughly speaking, the higher the R-value, the greater its insulating effectiveness.

So I was ready to find a warmer ultralight pad, and I was curious about Sea to Summit’s (S2S) new line of sleeping mats. I wanted to see how a product with such a small thickness could have such a warm R-rating (3.3).


One of the first things I noticed about this sleeping mat was how small it packs down, and how lightweight it is for an insulated pad. At about the size of a Nalgene when packed, I can slide it into my pack just about anywhere there’s a little air pocket between other items. When I first unrolled it and felt the material, it seemed impossible that this thing had any insulation because it was so thin. However, once you’ve inflated it and laid on it you can tell that there’s a lot more to this mat than just a couple layers of nylon (more on this in Features & Design below).

Andi Stader reviews the Sea to Summit UltraLight Insulated Mat for Blister Gear Review
Left to Right: Therm-a-Rest ProLite 4, Alps Mountaineering Nimbus, and Sea to Summit UltraLight Insulated Mat.

Once inflated, the UltraLight Mat is plenty wide for my shoulders and long enough that my feet do not come off the bottom. Even with my arm up under my head, I am still completely on the mat. The width and length of this mat are pretty much the same as most “regular” sized mats on the market (72”x20”x2.5”). My Alps Mountaineering Nimbus pad is 72”x20”x3.5” and my old Therm-a-Rest ProLite 4 (a self-inflating mat) is 72”x20”x1” (and 1lb 8oz), but the real difference is how small the Sea to Summit UltraLight packs down and how light it is.

Compared to several other insulated, inflatable sleeping mats on the market, at 15.5oz, the Sea to Summit UltraLight Insulated Mat is one of the lightest out there. For example, the Klymit Insulated Static V sleeping pad weighs 1lb 9oz, the Therm-a-Rest Evolite is 1lb 1oz, the Big Agnes Insulated Double Z weighs 1lb 5oz, and the Therm-a-Rest NeoAir Venture WV comes in at 1lb 6oz. Also, even though the UltraLight Insulated is the lightest in its category, it is very warm.

With a R-value of 3.3, the UltraLight Insulated Mat outshines both of the Therm-a-Rest mats mentioned above (the Evolite has a R-value of 2.1 and the NeoAir is an R-1.8). While the Klymit mat has an impressive R-value of 4.4 and the Big Agnes Double Z has a R-value of 4.5, these each weigh significantly more. So you’re trading off more weight in your pack for the difference between R-3.3 and R-4.5.

NEXT: Features & Design, Value, Etc.

3 comments on “Sea to Summit UltraLight Insulated Mat”

  1. Why would you choose this over the NeoAir X-Lite? Same R-Value, noticeably less weight? I’m surprised you didn’t mention the NeoAir X-Lite when you were talking about comparable pads.

  2. Lindahl, the NeoAir X-Lite is not an insulated pad, so I was only comparing insulated pads to insulated pads. Also, I haven’t used the NeoAir X-Lite myself, so I couldn’t compare anything else about it. But I would choose the Sea-to-Summit sleeping pads and their camping pillows over Therm-a-Rest products because of the amazing two-way valve and the ease of inflating/deflating because of that valve. It saved me tons of time on mountaineering trips at 2am!

    • Yes, the Neo air xlite is insulated with an r value of 3.2 and 350g (12oz) weight. A lot more expensive though in Australia at least. I currently use this pad and find it to be noisy, but that is the insulating foil that allows the map to achieve such an r value at the lower weight.

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