Home / Editors Choice / Sea-to-Summit Etherlight XT Insulated Sleeping Pad Review

Sea-to-Summit Etherlight XT Insulated Sleeping Pad Review

Sea-to-Summit Etherlight XT Insulated Sleeping Pad review

The Sea-to-Summit Etherlight XT Insulated Sleeping Pad is a lightweight, inflatable sleeping pad that is 4″ thick and features air-sprung cells for maximum comfort, making it far more comfortable than Thermarest’s NeoAir sleeping pads and much quieter. Weighing 15 oz, it has the same durable three-way inflation valve and is easy to inflate by mouth or with the included pump sack. Sea-to-Summit pads are also rated with R-values, so you can objectively choose the correct amount of insulation to complement a sleeping bag or quilt-based sleep system.

Sea-to-Summit Etherlight XT Sleeping Pad

Ease of Inflation
Packed Size

Super Comfortable and Warm

Move over NeoAir, there's a new boss in town. This Etherlight XT has air-sprung cells which are way more comfortable, with a durable flat valve, and soft cover fabric.

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Specs at a Glance

  • Weight: 15 oz
  • R-value: 3.8
  • Type: Inflatable
  • Dimensions: 72″ x 21.5″ (25″ widths and 78″ long lengths, also available)
  • Thickness: 4″
  • Insulation: Reflective platinum layer and synthetic insulation
  • Antimicrobial treatment: Yes
  • Included insulation sack: Yes
  • Materials: 30d / 40d nylon
  • Visit Sea-to-Summit for additional specs

Sleeping Pad R-Value Minimums

If you sleep on the ground with a quilt or sleeping bag on backpacking or camping trips, you need to use a sleeping pad with a minimum R-value of 4, if you want to experience the temperature rating of your quilt or sleeping bag. This may come as a surprise to many people, but it’s a well-established fact based on the existing EN sleeping bag temperature rating standard, and the new sleeping pad R-value standard, that will be rolling out to consumers in 2019 and 2020. To learn more, see my article about the new Sleeping Pad R-value Standard. It also explains why so many people sleep colder than expected even though they purchase quilts or sleeping bags that are supposed to keep them warm at their designated temperature ratings.

For example, if it’s 40 degrees at night and you have a quilt or bag rated for 40 degrees, you need a pad that has an R-value of 4 or more if you want to experience that 40-degree temperature rating. The same holds if it’s 20 degrees at night and you have a quilt or sleeping bag rated for 20 degrees. In other words, you can really shoot yourself in the foot if you sleep with an ultralight or uninsulated sleeping pad that has an R-value less than 4, if you need to count on the temperature rating of your quilt or sleeping pad. With an R-value of 3.8, the Etherlight XT Insulated sleeping pad is close enough to an R-value of 4, to satisfy this requirement.

The Etherlight XT Insulated Mat is a super comfortable sleeping pad

Comfort and Quiet

The sleeping surface of the Insulated Etherlight XT is made up of air-sprung cells, which mimic a pocket spring mattress so that the surface of the pad conforms to your body shape regardless of whether you sleep on your back or on your side. This helps keep you on the pad at night, without the need for extra side-rails to keep you from rolling off. These air-sprung cells are far more comfortable than the horizontally oriented surface of Therm-a-Rest’s NeoAir pads, which begin to feel like wooden boards if you sleep on them for more than a few nights in a row.

While the Insulated Etherlight XT is heavier than a NeoAir Xlite (R-Value 3.2) and has a lower R-Value than a NeoAir Xtherm (R-Value 5.7), it is 1.5″ thicker than the 2.5″ thick NeoAir pads and made with heavy duty 30d/40d fabrics for increased durability. The added comfort of a thick pad and the air sprung cells is so worth it, especially on multi-day trips when sleeping well is essential. The Etherlight is also insulated with synthetic fibers and not just a reflective layer, making a much quieter pad to sleep on.

Flat valve closeup
The Etherlight XT has a flat three-way valve (twig not included)

Flat Valve and Pump Sack

The Etherlight pad comes with its own pump sack for ease of inflation. It mates to the pad’s flat valve, which is a three-way valve: one for inflating the pad, with an integrated nipple that lets you release air for more comfort, and a closed cap for closing the valve completely. If you lift both caps to deflate the pad, the air quickly rushes out of the big valve hole, so you don’t have to spend time evacuating the air or rolling up the pad multiple times to force it all out (like a NeoAir). Flat valves are also much more durable than stick valves since they don’t require a screw-type lock and roll up flat.

Pillow attachment system
The Pillow Lock attachment system ensures that your pillow stays attached to the pad all night

Pillow Attachment

I’ve never been one for backpacking pillows, but the Pillow-Lock attachment system that comes with the Etherlight XT has made me a convert.

The Etherlight XT comes with 4 velcro pads that you can stick to the top of the pad. These hold a Sea-to-Summit pillow in place so it doesn’t move off the pad at night. It works great. I was on a two-week trip this spring where I used this feature every night and it greatly enhanced my sleep experience and comfort. I used a 2.5 oz Sea-to-Summit Aeros Down Pillow, but the pillow-lock system works with any of the Sea-to-Summit’s inflatable pillows.

Comparable Sleeping Mats

Make / ModelR-ValueWeightThickness
Sea-to-Summit Insulated Etherlight XT3.815 oz4.0"
Sea-to-Summit Comfort Light Insulated Mat4.221.8 oz2.5"
Therm-a-Rest NeoAir Uberlite2.08.8 oz2.5"
Therm-a-Rest NeoAir XLite3.212 oz2.5"
Therm-a-Rest NeoAir XLite Women's3.912 oz2.5"
Therm-a-Rest NeoAir XTherm5.715 oz2.5"
Exped DownMat UL7.022.2 oz3.5"
Exped SynMat HM5.015.2 oz3.5"


The Sea-to-Summit Insulated Etherlight XT sleeping pad is a super comfortable sleeping pad with air-spring cells that mimic a spring mattress. A full 4 inches thick, it conforms to your body shape and keeps yon the pad all night regardless of whether you’re a back or side sleeper. A flat valve and durable exterior fabric increase durability and reliability, while an R-value of 3.8 helps ensure that your sleep system will perform optimally at the temperature that it is rated for. Highly recommended!

Disclosure: Sea-to-Summit provided the author with a pad and pillow for this review.

Editor's note: Help support this site by making your next gear purchase through one of the links above. Click a link, buy what you need, and the seller will contribute a portion of the purchase price to support SectionHiker's unsponsored gear reviews, articles, and hiking guides.

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  1. I appreciate that they offer a 72″ x 25″ pad. Has anyone compared the women’s to men’s? It would be interesting to know how they truly differ.

  2. Great timing on the review. Was considering this or the revised Nemo Tensor while the REI member sale is still on, and I like the idea of the tougher fabric in the S2S mattress. Are there any other notable differences between them?

  3. Being old just got a little bit easier…

    • I just bought one for my wife and can confirm that the inflation sack works with the current Thermarest stick valves. It fits nicely into the inside of the bag’s nozzle.

      • langleybackcountry

        I do not understand how this would work. The shape of the valve is completely different and the S2S pump sack makes a positive connection sealing with the valve.

  4. Wished they offered a Regular Length in the Wide 25″ size. Only Nemo seems to offer this. I’m 5′ 6″ and find my arms laying on the cold ground using regular pads that are ~ 21″ wide. And I don’t need the extra 1′ length of the long pads which do offer the wider width. I know there are DIY approaches (scissors and iron) to take a Long/Wide and turn it into a regular length/wide but who wants to spend top dollar and have to modify it to make it right.

    • They do offer a reg wide pad at 72 in x 25 in

      • Hi Joe, I think that’s the rectangular size which still weights about the same as the long/wide model. Or am I overlooking something?

      • You’re correct its the rectangular one. There is no reg wide mummy version.

    • It looks like you can get the women’s in a sort of mummy shape st 72 x 25.

      • Thanks Cheri. That does look like a good size.

      • I bought the S2S Women’s Ultralight Insulated Air Sleeping Mat, size large (25”x72”) and like it. Even the paprika color! I’m male, 6’2”, 180 pounds. It’s a good length and width for me. S2S says it’s narrower at the shoulders than the “unisex model”. It is comfortable, quiet, and warm at least to the upper 40s, the temps I used it in April. And that pumpsack is great! I have to say I’m tempted by this Etherlight XT, but I’m a bit concerned that a 4” thickness will boost me too high in my tents and bivys.

    • And the women’s is on sale at REI for $157. I don’t know how the shape differs but may not be a bad idea to order it and find out.

  5. Unfortunately that free pillow code doesnt appear to be working.

    • Doesn’t work for me either. I just shot off a complaint to Sea-to-Summit. I’ll let you know what I find out.

      • Sea-to-Summit’s response re: the FreePillow coupon code.

        it’s only applicable for the Aeros Premium, Aeros Ultralight and Foam Core pillows (which isn’t exactly what their banner says), but it is what it is, I guess.

  6. Any thoughts on how this compares to the Big Agnes AXL?

  7. Thanks, Philip for this review of the S2S Insulated Ethernet XT, it sounds like a good lightweight solution for UL backpackers who want some extra comfort like me. Can you describe the pad fabric surface? Is it a soft fabric feel suitable for using a comforter, like the new Nemo Tensor? And I’ve heard comments on other blogs that the pad surface feels like plastic and slips around on their tent floors,…..your thoughts, please?

    • Perfectly comfortable to sleep on. Thicker denier covering fabrics are like that. All pads slide on sil, PU or DCF floors. You get a small 1 oz piece of Gossamer Gear thinlight pad to put underneath that doubles as a sit pad. Well known UL hack.

  8. Just got one of these and spent a few nights on it. Really comfortable, more so than Thermarest. I think this will be a popular mat for those who don’t mind carrying a few more grams for a decent nights sleep.

  9. A few questions: Is a little patch kit included with this pad? Is the Exped Schnozzel inflation bag compatible with the valve on this (without needing any kind of adapter)? Is the “Pillow Lock” attachment a hook-and-loop system? If so, are the tabs on the pad hooks or loops? Aside from generally disliking hook-and-loop (wears out over time, ruins things like socks that accidentally get attached), i’m moving to a quilt for warmer weather and will be using it with a pad cover/sheet that i wouldn’t want to attach to the “Pillow Lock.” I guess i could just attach some little piece of the complementary fastener to the tabs to “deactivate” them.

  10. The pad comes with it’s own pump bag. Is there a reason you used a different one? Did you remove/cut out the one it came with?

  11. Hi Philip! Thanks for the review. It sounds like you really, really like this pad. Are you switching from the Thermarest NeoAir XLite to this pad for 3 season backpacking? Would the STS Etherlight XT pad be warm enough for you personally when coupled with your Thermarest ZLite Sol sleeping pad for winter backpacking and camping? Would you think the two pads (STS pad toether with the ZLite Sol) would be warm enough for someone who sleeps cold for winter camping?

  12. langleybackcountry

    I got this pad about a year ago and it changed my life. I was disappointed with the S2S Insulated Ultralight, and I have an old XTherm. They will probably just go into my backup/loaner bin. The S2S valve is the best, and the thickness as a side sleeper makes a huge difference.

  13. Another happy user here.

    I got interested in the pad when I read that leading reviewers in the UK were choosing it for personal use, plus the manager and half the staff at my local outdoor store.

    I’m a 5’10” male, but bought the large woman’s for the extra size and insulatation. The lozenge shape is great for side-sleepers – for the first time ever my knees aren’t hanging over the edge of my pad, and it makes a surprising difference to comfort and warmth. The width at the shoulders if fine for me, even though I’m quite stocky. Combined with edges that are far more supportive than other pads I’ve used, I’ve just spent a week without falling off the pad once and seven nights in a row where I had uninterrupted sleep all night. This is a first for me in half a century of wild camping – the most comfortable pad I’ve ever used, by some margin.

    My other priority is reliability. I’m very gentle on my sleeping gear, but I’ve had my fill of failed valves and blown welds. StoS say that they chose a more expensive and reliable welding technology than competing mats, and that the fabric was selected because it was the lightest that would hold a reliable weld. I had a chat and they are claiming that they haven’t had a single failed weld to date, which is impressive if true. Plus the valve looks robustly designed and repairable in the field using the spares in the patch kit, unlike the Exped valve…

    As a walker of “a certain age” I’m beginning to prioritise quality of sleep of weight, and the extra few grams are well worth it to me, as was the premium price. If it’s as durable as claimed, this is a best buy for anyone but the most obsessive gram-counter.

  14. Looks like a great mattress. I have a similar REI FLASH Insulated air mattress that uses a Sea to Summit valve and the compatible inflation/dry bag. It has a R 3.7 value which is “close enough” to the recommended R4.

    I’m concerned that my REI FLASH mattress may not be as durable as the StS Etherlite mattress. Field reports have not been good but REI says they will stand behind them IF it’s a manufacturing flaw, which most reported failures have been as welds failed.

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