REVIEW: Sea to Summit Ether Light XT Extreme Insulated Air Sleeping Pad

Sea to Summit
XT Extreme Air

Reviewed by:
On May 14, 2022
Last modified:May 16, 2022


If you're going on a cold-weather adventure and need a sleeping pad to help keep you warm, this is the one you want. While it is a bit bulky and noisy—which is to be expected from an insulated pad—it is comfortable, warm, and durable. Exactly what you need when facing harsh winter conditions.

Sea to Summit Ether Light XT Extreme

If you’ve ever been on a winter camping trip or gone on an excursion in extremely cold conditions, you probably know how challenging it can be to get a good night’s sleep. Even snuggled into a warm sleeping bag, it can be challenging to get rest while lying on the hard, frozen ground. An insulated sleeping pad can help alleviate those issues by serving as an additional barrier against the frosty conditions. But not all insulated pads are created equal and some are designed for use in truly frigid environments.

That isn’t the case for Sea to Summit Ether Light XT Extreme Insulated Air Sleeping Mat, which has been specifically constructed to take on the harshest of conditions. This pad features a unique design and construction that gives it some advantages over other sleeping pads, which cold weather adventurers will definitely appreciate.

Design (5) ★★★★★

As usual with Sea to Summit, the Ether Light XT is an overengineered product. The company used four-inch-thick, interconnected air-sprung cells to add comfort and protection. Those cells help keep campers off the ground and provide exceptional comfort when lying flat. A dual-density layer of Thermolyte insulation is added to limit heat loss and create additional warmth. The entire mattress is then covered in a durable and soft liquid-extruded face fabric that provides a high degree of protection while keeping weight to a minimum.

All of these components come together to create a sleeping pad that is unlike anything else on the market. It is thick, warm, and acts more like the mattress you have on your bed back home. Despite being so comfortable, it is also too warm for use on normal camping or backpacking trips, but is perfect for its intended purpose of cold-weather outings.

Weight (5) ★★★★★

The Ether Light XT Extreme weighs in at 1 pound, 9 ounces (720 grams). At first glance, that seems like a big number, making this a very heavy sleeping pad. But when you consider that this mat is meant for use in very cold weather, that weight isn’t bad at all.  In fact, when you take into account all of the design work and materials that went into creating this pad, it’s actually quite light. Yes, ultralight hikers would never consider using a pad of this weight, but then again you probably shouldn’t be going ultralight during the winter anyway. In order to stay safe and warm, your sleep system needs to be a bit heavier and thicker than the one you use in warmer conditions. When viewed from that context, the Ether Light XT is surprisingly light considering its performance and features.

Sea to Summit Either Light

Performance (5) ★★★★★

Speaking of performance, Sea to Summit says that Ether Light XT Extreme has an r-value rating of 6.2. If you know anything about temperature ratings for sleeping pads and sleeping bags, you probably already know that is a very good number. You probably also know that r-ratings are somewhat subjective.

That said, Sea to Summit is one of the few companies in the outdoor space that doesn’t tend to over-exaggerate its r-value ratings. It is also one of the few companies that has its own testing facility. Most other brands outsource the testing, which can introduce greater variance in the scores. But if Sea to Summit says this pad has a 6.2 rating, it is probably pretty close to spot on. To put that number into context, most three-season sleeping pads have an r-value in the 2-3 range and many insulated models fall into the 4-5 category. This puts the Ether Light XT Extreme well above most of the competition.

R-value ratings aside, it’s how a pad performs in the field that really counts. In this case, you can rest assured that Sea to Summit has a winner in this mattress. It is warm, comfortable, and everything you could ask for in an insulated pad. Unless your travels take you into extreme arctic conditions, the Ether Light XT Extreme should perform admirably.

Overall (5) ★★★★★

If you’re in the market for a new sleeping pad for use on cold-weather adventures, this is the model for you. Like other insulated pads, it is a bit bulky and a little noisy when trying to sleep, but that is not uncommon for these types of mats. Those minor quibbles aside, the is the best sleeping pad we’ve seen for use on winter camping or backpacking trips. For warmth and comfort, it is tough to top.

The Ether Light XT Extreme’s $200 price point is another number that may stand out. Make no mistake, this is an expensive sleeping pad when compared to the thinner, lighter three-season models on the market. But again, in the context of the insulated sleeping mat space—especially those meant for use in extreme conditions—that is a relatively good price. If you’re a veteran winter camper you’ll immediately recognize the value that this pad offers and even more so when you use it in the field.


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Yoon Kim

Yoon is a freelance journalist who writes for SNEWS, The Outdoor Retailer Daily, Retailing Today, Gear Junkie, and many more. He writes mostly on outdoor topics including business, gear, event coverage and interviews with outdoor athletes. Yoon is an Insanely Big Mountain.

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