Sea to Summit Ether Light XT Extreme Review | 6.2 R-Value Winter Pad

When cold weather hits, you need a good pad with a high R-Value in order to stay warm. A Sea to Summit Ether Light XT Extreme review was definitely in order as soon I saw that Sea to Summit had come out with this new cold weather mat. I’d been waiting for Sea to Summit to come out with this pad after getting the chance to test out the Ether Light XT Insulated version (3.2 R-Value). While I love the Ether Light XT Insulated, it simply wasn’t going to cut it for colder weather hunts or winter hiking trips. Enter the Ether Light XT Extreme.

The Testing: Sea to Summit Ether Light XT Extreme Review

With the success we’ve had with the Sea to Summit Ether Light XT Insulated Pad, hopes were high for this Sea to Summit Ether Light XT Extreme. There aren’t a ton of pads on the market that are light enough for backpacking, yet warm enough for cold weather trips when temperatures drop well below freezing and even below zero degrees Fahrenheit. This impressively lightweight pad comes in at just 25.4 ounces with a super comfortable 4 inch thickness and comes in multiple sizes: regular and large (mummy shaped), rectangular regular, and rectangular large.

Sea to Summit Ether Light EX Extreme Pad Review

For this Sea to Summit Ether Light Extreme review, we were able to have two team members test it out; one in the Idaho backcountry, and the other in the mountains of Colorado, so we were really able to put this thing to the test in multiple situations and in multiple locations over the course of a year.

Looking for a pad that is perfect for a little warmer weather? Check out our other sleeping pad reviews for more ultralight (and comfort) pads we’ve tested and reviewed (including the Ether Light XT Insulated)!

Sea to Summit Ether Light XT Extreme Specs

Ether Light XT Extreme Specs (Reg)
Weight 25.4oz
Packed Size 6.9in x 9.4in
Insulation Thermolite
Shell Weight 5.1oz
Width 20in
Material 30D/40D
Thickness 4 inches

Edge-To-Edge Stability: Sea to Summit Ether Light XT Extreme Review

Sea to Summit Ether Light XT Extreme Review

The Sea To Summit Ether Light XT Extreme gives you fantastic edge-to-edge stability, especially considering that it’s 4 inches thick. Other pads that we’ve tested that are this thick can sometimes make you feel like you are going to roll off when you get close to the edge of the pad, but not the Ether Light XT Extreme.

The Feel: Ether Light XT Extreme Review

Sea to Summit Ether Light XT Extreme Review

The Sea to Summit Ether Light XT Extreme gives you a thick, cushy mat that is still fairly quiet (for an ultralight pad). It’s similar in feel to the other Sea to Summit pads we’ve tested, but a bit noisier than the Comfort Plus or the Ultralight Insulated pad we’ve tried out. Being 4 inches thick, you do get a very slight waterbed feel, but it’s far less than I expected. Those air sprung cells give this pad excellent stability.

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Like the Ether Lite XT pad, I found the material to be a little slick, particularly when the temperatures drop, as my sleeping bag tended to slide on the pad at little. This is a common issue with an air mattress and certainly nothing worse than any of the other pads I’ve tested. A pad attachment system or pad straps for a quilt (or finding a flat camp site) solve that issue. I’ve also started putting some non-slip tape on the bottom side of the pad and/or tent floor and that helps a ton as well. Check out this video!

Noise Factor: Sea to Summit Ether Light XT Extreme Review

Seek Outside Cimarron Light Review

The Sea to Summit Ether Light XT Extreme is a little bit on the noisy side, but nothing that bothered me. While it’s nowhere near as loud as the Thermarest NeoAir X-Lite, it’s not as quiet as some others I’ve tested like the Exped Downmat or Exped Synmat.

Sea to Summit Pillow Lock System

Sea to Summit Ether Lite XT Extreme Review

The Ether Light XT Extreme comes with an optional pillow lock system that is compatible with all Sea to Summit pillows and really any fleece style pillow for that matter. This system is similar to Velcro and keeps your pillow from getting away from you at night. I found that I really like this system as it works not only with Sea to Summit Pillows that offer the pillow lock system, but also with any pillow that is covered in a material that will stick to Velcro.

I’ve always had a problem with my pillow getting away from me at night, so this Pillow Lock System is a huge bonus for me!

Gabe’s Experience: Sea to Summit Ether Light XT Extreme Review

Seek Outside Cimmaron Tent

Lower Temperature Limit

I was able to use this Sea to Summit Ether Light XT Extreme pad on a number of cold weather, late season hunts that really brought out the good and bad on this pad. I found that making sure the pad is fully inflated, even uncomfortably so, gives it the most temperature range. While I typically like to leave my pad a little on the soft side, I realized by doing that, the Ether Light XT Extreme would lose some of its insulating abilities. The folks at Sea to Summit said to try fully inflating the pad to get the best performance out of it, and I found this to be true.

Seek Outside Cimmaron Tent

With that being said, I found the lower limit of this pad to be right around the -5 degree range. With an R-Value of 6.2, I felt like I should have gotten a bit more out of it, but I could just barley start feeling a little cold around the -1 degree mark. At the -1 degree temperature, I would be warm as long as I didn’t move, but as soon as I rolled over, the movement of air in the pad would create a cold spot. It would warm up fairly quickly as long as I didn’t move.

Comfort

Sea to Summit Ether Lite XT Extreme Review

I thought the Ether Light ET Extreme was super comfortable all the way around. You can’t ask for much more in a 25 ounce winter mat in the comfort department. Sea to Summit’s Air Sprung Cells do a wonderful job of giving you stability and comfort.

Durability

The Sea to Summit Ether Light XT Extreme is made of 30D / 40D nylon face fabric (same as the Ether Light XT Insulated), but I did have this mat pick up a couple holes on my second use. I’ve had great luck with this fabric on the Ether Light over the years as it’s held up well, however, the timing of getting this hole was quite bad as temps dropped down into the low teens which made for a cold night.

Sea to Summit Alpine Sleeping Bag Review

I patched it up with the kit that’s included and it was good to go and has worked perfectly ever since, but it wasn’t a fun night on the mountain in November. I will say that the patch job was extremely easy and fast as the patch kits Sea to Summit provides make the job very easy. Locating the puncture hole can be a challenge at times, but once located, it’s a super fast fix.

Gabe’s Final Thoughts on the Ether Light XT Extreme

Sea to Summit Ether Lite XT Extreme Review

Overall, I really like the Sea to Summit Ether Light XT Extreme air mat. I found it to be great down to around -5 degrees, but also thought it would do a bit better than that given its robust R-Value of 6.2. I really like the pillow lock system and found that to be a game changer when bundled up in a sleeping bag. This allows you to keep the pillow outside the sleeping bag sealing out the cold air rather than trying to fit the pillow in the sleeping bag hood or chase it around all night long.

I also love how comfortable it is. Over the years I’ve loved Sea to Summit’s Air Sprung Cells, and it was no different with the Ether Light XT Extreme. As far a durability, I do wish the face fabric was a bit more robust, but then again, that’s the tradeoff for the weight savings you get with this mat. A few cold nights on the mountain in November and you’ll quickly re-consider weight savings vs durability. You can’t have it all unfortunately!

Sea to Summit Ether Lite XT Extreme Review

The Ether Light XT comes with an integrated Air Stream Pump Sack, which makes filling the Ether Light a breeze. It only takes 3 pumps to fill the regular size pad. I love that the stuff sack the Sea to Summit Ether Light XT Insulated Pad comes with doubles as a pump sack. It can be a chore to blow up a pad after a long day of hiking, so the ease with which the pump sack makes filling the pad is a welcomed bonus.

Luke’s Experience: Sea to Summit Ether Light XT Extreme Review

Sea to Summit Ether Lite XT Extreme Review

Lower Temperature Limit

I had the opportunity to sleep on this pad using the Feathered Friends Eider EX -10 sleeping bag, a bag that has more than enough capability to really put this Sea to Summit Ether Light EX Extreme pad to the test on the extreme end of its lowest limits. I was able to test this pad in temperatures from 10 degrees Fahrenheit all the way down to -15 degrees. The pad is very comfortable and quiet allowing you to get a good night’s sleep on it.

Sea to Summit Ether Light EX Extreme Pad Review

The first night that it was just below zero I did not have the pad fully inflated as I generally like having a little more cushion while I sleep. After this experience, the folks at Sea to Summit recommended inflating the pad fully to maximize the warmth of the pad. Doing that got me down closer to -5 comfortably.

I also noticed that if I didn’t move around much, the pad was warmer, however, if I tossed and turned my movement pushed the air around in the pad and there were some temporary cold spots until my body heated up the air again. It was not unbearable as long as I did not move around too much. I do tend to roll around in my sleep quite a bit and noticed the cool air more and more as the sub-zero nights went on. It was not enough to make me overly cold at 0 to -5, but I definitely got a slight chill.

Sea to Summit Ether Light EX Extreme Pad Review

I was hoping to be able to get into sub-zero temperatures comfortably, but unfortunately for me I started to notice some cold coming through the pad at around 0 degrees. Now I know that I am a cool sleeper, so you may get more out of it than I did if you tend to sleep warm, but each night that it went sub-zero, I noticed the cold slowly creeping up from the ground.

In all reality this pad is a phenomenal option for most parts of the year and will perform flawlessly in very cold temperatures, but if you are wanting a winter sleeping pad to get you much below the -5 degree mark, I’d recommend going a different route. I wouldn’t hesitate to take this pad and use it in single digit temperatures or warmer.

Pad Comfort

The Sea to Summit Ether Light XT Extreme is wide enough to move around comfortably without falling off of it, and also allows you to lay flat on your back with your entire body being on the pad. I’m 6’3” and 220 pounds and had enough room to lay flat on my back without my shoulders falling off the sides. It also does a good job of weight distribution while sleeping on your side, which I do frequently. I never felt the ground while sleeping on my side, even when the pad was not fully inflated.

Pad Durability

During my testing the Sea to Summit Ether Light XT Extreme, I had zero issues with durability. The pad never lost any air, deflated in any way, and was never punctured. Sea to Summit stands behind their products, so I know if I ever do have any issues, they have a great warranty and will make it right.

Things Luke liked

There is a lot that I really like about the Ether Light XT Extreme pad. I love how easy it is to fill up, the functionality of the valve system, how quiet it is during use, and the fantastic pillow lock system. The air sprung cells are a huge component in the design of the Ether Light XT Extreme that really makes this pad so comfortable.

Sea to Summit Ether Lite XT Extreme Review
  • Extremely comfortable with a generous 4 inch thickness
  • Very easy to fill up with the pump sack
  • One valve for inflating and deflating
  • Relatively quiet
  • Pillow lock system
  • Pump sack is built into the storage sack
  • Wide enough that you don’t touch the ground on either side while lying flat on your back

Things Luke Didn’t Like

Even though overall I was very pleased with the Ether Light XT Extreme pad, there are a few things that I thought could make the pad better. I had hopes of using the pad well below zero, but that didn’t pan out for me. I also wish it didn’t need to be inflated fully in order to maximize its warmth. For me, the pad isn’t as comfortable when fully inflated, but that’s a personal preference.

  • Wasn’t as warm as I hoped at the lower limits.
  • Had to fully inflate to maximize warmth at the lower limits

Our ratings for the Sea to Summit Ether Light XT Extreme

Price
Weight
Durability
Quality
Packability
Warmth
Overall Ranking

Conclusion

The Ether Light XT Extreme is very impressive in its comfort, thickness and packability for a pad with a 6.2 R value. We loved the pillow lock system and easy inflation with the included pump sack. While we both were hoping to get a bit more from the 6.2 R-Value, it’s still an impressively warm pad that we found to be good down to around zero before any hint of cold air was felt. For most of us, that will take care of most situations we are in and more. However, if you are needing a cold weather pad that’ll get you well into the negative temps, other options might serve you better.

If you are looking for a great late season pad that will comfortably get you down to that zero degree Fahrenheit range, definitely give the Sea to Summit Ether Light XT Extreme a look. It’s a great pad that is super comfortable, packable, and features a great pillow lock system to keep your pillow from running away from you at night.

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2 thoughts on “Sea to Summit Ether Light XT Extreme Review | 6.2 R-Value Winter Pad”

  1. Hey thanks for this. I’ve got their two layer matreesses in the normal and insulated versions and love them… they got me willing to do overnight hikes. But i always carry an extra under layer. Overseas its a windscreen sunshade thing and at home a thin aluminized foam roll up mattress. With a decent bag, liner and thin layer of clothes I’ve slept comfortably in much lower temperatures than the basic mattress would suggest is OK. And hey, I’ve had no leaks but I know I’d fix them immediately! When camping, I expect random things will happen and just deal with them. Cheers!

    Reply
    • Thanks John! Yeah, there are certainly ways to extend the effective temperature of a pad by adding layers and/or putting layers between you and the ground. Thanks for reading and happy backpacking!

      Reply

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