Sea to Summit Ether Light XT Insulated Review: For Big Comfort For The Backcountry!

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Ultralight meets ultra-thick: We took the Sea To Summit Ether Light XT Insulated out into the backcountry to see just how comfortable a four-inch thick pad can be!
Sea to Summit Ether Light XT Insulated - Introduction
The Sea to Summit Ether Light XT Insulated raises the bar for comfort by adding warmth to one of the thickest backpacking mattresses on the market.

The Sea to Summit Ether Light XT Insulated

– Price: $189 – $229
– Weight: 1lbs/0.45kg (short mummy), 1.1lbs/ 0.5kg (regular mummy), 1.4lbs/ 06kg (large mummy)
– R-Value: 3.2
– Dimensions: 66” x 21.5” x 4”/ 168cm x 55cm x 10cm (short mummy), 72” x 21.5”x4”/ 183cm x 55cm x 10cm (regular mummy), 78” x 25” x 4”/ 198cm x 64cm x 10cm (large mummy)
– Packed Size: 9.5” x 4.5” / 24cm x 11cm (short mummy), 9.5”x4.5”/ 24cm x 11cm (regular mummy), 11” x 4.75”/ 28cm x 12cm (large mummy)
– Pad Type: Insulated air
– What we like: Super comfortable, durable, versatile
– What we don’t: Expensive, not the lightest, not the warmest

The Wise Adventurer’s Verdict

Sea to Summit Ether Light XT Insulated - TWA Verdict
We found the largest rectangular version of the Ether Light XT to be a bonafide luxury, assuming you don’t need to share your tent with anyone else.

This is The Wise Adventurer’s field test and review of the Sea To Summit Ether Light XT Insulated, an utterly premium backpacking sleeping pad with a sharp focus on comfort and durability. We bought it and fully tested it just for you!

The Sea To Summit Ether Light XT Insulated holds a special place on the backpacking scene: It’s compact and impressively light at just 17oz, yet it somehow manages to deliver a full four inches of thickness as well as three season-worthy warmth and insulation. 

This combination of innovation and practicality is exactly the kind of thing we love about Sea To Summit gear. In our experience, Sea To Summit’s stuff just plain works, which makes sense considering the brand’s testing ground centers around the remote expanse of the Australian Outback. 

We spent several months living with the latest Ether Light XT Insulated, and had the pleasure of bringing it along for camping and backpacking trips in a wide variety of seasons and climates. During that time we subjected the Ether Light to our universal testing procedure and methodology and took detailed notes along the way, so if you want to see how it stacks up to the competition, keep reading!

Detailed Evaluation Of The Sea To Summit Ether Light XT Insulated

As part our yearly testing of the best sleeping pads, our aim in field testing the Sea To Summit Ether Light XT was to put the sleeping pad through all the most common scenarios campers will encounter when using the pad themselves. This gave us the opportunity to evaluate important performance metrics like comfort and packability, while also identifying any potential weaknesses of the pad over time.


Comfort is the Ether Light’s single greatest feature, and like all of Sea To Summit’s “XT” pads (that’s short for “extra thick” by the way), the Ether Light XT Insulated absolutely delivers the goods. Our testers attribute the pad’s impressive coziness to two things: Its four-inch thickness, and its unique “Air Sprung Cell” design. 

We had our first experience with Sea To Summit’s unique “Air Sprung” baffle technology last year while backpacking with the Ether Light XT Air, and we’re big fans of what the brand’s done here. Essentially the Ether Light XT (and other Sea To Summit sleeping pads like it) forego traditional vertical or horizontal baffles in favor of dime-sized welds, which are spread over the pad in a diamond quilted pattern. 

Sea to Summit Ether Light XT Insulated - Comfort
The Ether Light’s unique “quilted” surface is made up of dozens of small welds, allowing the pad to be impressively thick and comfortable without the usual bouncy air-mattress feeling.

The result is an incredibly thick and comfortable sleeping surface with oodles of adjustable firmness to spare. Typically air pads this thick feel bouncy and unstable as you roll around on them throughout the night, but our testers reported no such issue with the Ether Light XT Insulated. 

Our testers also remarked that the Ether Light’s added thickness made it a perfect companion for the side sleepers in our group. Air sleeping pads often lose a bit of thickness as temperatures drop throughout the night, which can lead to discomfort on thinner models. The extra volume of the Ether Light leaves plenty of room to spare, however, and never left us with a shoulder or hip on the ground throughout our testing. 

Weight And Packed Size

If there’s one thing keeping the Ether Light XT Insulated from the top of most backpackers’ wish lists, it’s packability. While the pad is neither heavy nor bulky, it’s a bit larger and heavier than many of the pads it competes with. The Therm-a-Rest Neoair XLite NXT and Nemo Tensor Ultralight Insulated may look better on paper, but you shouldn’t rule the Ether Light out on specs alone. 

We tested both the mummy and rectangular versions of the pad, the smallest of which weighed in at 1 pound, while the largest rectangular sleeping pad tipped our scales at 1.5 lbs. Ultimately we found our favorite option in the large-sized mummy bag, which split the difference between the two while still being suitable size-wise for multi-day backpacking use. 

Sea to Summit Ether Light XT Insulated - Weight and Packed Size
The Ether Light Xt Insulated looks a bit oversized next to its insulated competitors (especially in the large/rectangular size seen here), but we found it’s added plushness well worth the extra bulk.

The Ether Light XT definitely feels large when compared side-by-side to pads like the Nemo Tensor, but once our testers had it out in the backcountry, they were glad they’d brought it. The XT Insulated’s class-leading thickness and extra surface area are a serious treat after a long day on foot, and we never found ourselves wishing we’d left it behind in exchange for more space in our packs. 


The Sea To Summit Ether Light XT Insulated gets an R-value of 3.2, which makes it well suited for spring-to-fall use. As far as insulated sleeping pads go, it was definitely on the lower end of the spectrum in our recent field test, with most of the competition sporting R-values of 4 or better. 

With that being said, we spent several nights in the desert this fall backpacking with the Ether Light XT Insulated, and found it to be plenty cozy for temperatures down into the mid-30s when paired with an appropriate sleeping bag. We wouldn’t recommend it for use during cold weather trips in temperatures below freezing, but with the help of an additional foam pad, it could definitely go the distance year-round. 

Sea to Summit Ether Light XT Insulated - Insulation
Reflective fabric and synthetic fill provide warmth, while the Ether Light’s air cells limit circulation of air within the pad.

Naturally we’re a little disappointed that the XT Insulated falls short of its competitors in this regard, especially considering its premium price. It still reigns supreme in terms of overall thickness and comfort though, so if you have no interest in camping during the winter, you won’t miss the extra warmth. 

Ease Of Use 

Our testers reported the Sea To Summit Ether Light XT Insulated was among the most user-friendly sleeping pads we’ve tested to date. Sea To Summit included a host of innovative design elements in the Ether Light, all of which make the pad that much easier to live with. 

For starters, we’re big fans of the pad’s included pump sack. Sea To Summit takes a unique approach here by integrating the pump sack into the carry bag itself, which makes for an extremely effective design as well as the quickest inflation sack of the bunch. 

Sea to Summit Ether Light XT Insulated - Ease of Use
The Ether Light’s pump sack is outstanding, as is the optional “pillow lock” system, which locks your camp pillow in place between the pad and your sleeping bag with velcro strips.

Our testers also appreciate Sea To Summit’s innovative “pillow lock” system, which uses four small adhesive velcro strips to secure Sea To Summit branded pillows between your sleeping pad and sleeping bag. It’s an optional feature (the velcro strips come with the pad, but the pillows are sold separately), but a nice one to have just the same, especially if you roll around a good bit during the night and find yourself constantly coming off your pillow.


The Ether Light XT Insulated is among the most durable backpacking pads we’ve used to date, going toe to toe with heavyweights like the Big Agnes Rapide SL Insulated we tested it alongside. Much of this is due to the pad’s tough 30D/40D face fabric, with the heavier material protecting the bottom of the pad from abrasion and punctures. 

Sea to Summit Ether Light XT Insulated - Durability
The Ether Light XT Insulated’s mix of 30D/40D nylon is among the toughest stuff we’ve seen in an ultralight to date.

Our testers reported no issues after spending several nights on the Ether Light XT in the middle of the unforgiving deserts of Utah, which are notoriously laden with thorns, noxious weeds, and rocks. The Ether Light XT also benefits from Sea To Summit’s liquid-extruded lamination process, giving an extra tough look and feel to the pad’s welded seams. 


Overall, we felt that the Ether Light XT Insulated made a strong argument for value. While it’s without a doubt one of the more expensive backpacking pads we’ve tested this year, it’s by no means the most costly, yet clearly one of the most premium and durable options. 

Sea to Summit Ether Light XT Insulated - Value
Comfortable, easy to use, and impressively durable, we found the Ether Light XT the ideal companion for three-season camping and backpacking missions.

We feel the lack of four-season insulation is a bit of a letdown, especially considering there are less expensive and warmer alternatives out there like the Big Agnes Rapide SL Insulated. Still, the Ether Light XT Insulated remains undefeated in terms of overall thickness, so if comfortable three-season camping is your main focus, we believe this pad will be well worth the investment. 

What We Like

Comfort is the single biggest selling point of the Ether Light XT, and our testers all agreed that it was either the most comfortable pad in our testing, or tied for the top spot alongside heavy hitters like the Big Agnes Rapide SL. This was the thickest air pad overall of our recent field test, making it super comfy, and the side sleepers in our group had nothing but praise for the XT’s bed of plush air-sprung cells. We also appreciated some nice features, like the “pillow lock” system.

Sea to Summit Ether Light XT Insulated - What We Like
Go ahead and dig those elbows in: With four inches of air between you and the ground, the Ether Light XT Insulated is the perfect pad for side sleepers.

Combine that outstanding comfort with durable materials, innovative construction, and one of our favorite pump sacks on the market to date, and you’ve got the makings of one of the best all-around air pads money can buy. The Ether Light Insulated may not be the lightest or most compact option out there, but it lacks nothing in terms of quality or comfort for three-season use. 

What We Don’t Like

The biggest letdown we found in the Ether Light XT Insulated was its R-value. While a 3.2 rating promises ample warmth for three-season use, most of the competition delivers an R-value of 4 or higher and does so for no additional charge or weight penalty. 

Sea to Summit Ether Light XT Insulated - What We Dont Like
While the Ether Light XT Insulated is a great backpacking pad overall, there’s definitely room to improve in terms of size and weight, especially considering its three-season limitations.

Speaking of which, we found both weight and packed size left something to be desired in the Ether Light. While the pad was fully serviceable for multi-day backpacking trips, there’s no denying there are smaller and lighter options out there for those willing to sacrifice a modest degree of comfort. 


Our Final Thoughts About The Sea To Summit Ether Light XT Insulated

While the Sea To Summit Ether Light XT Insulated may not look like a standout offering on paper, we found this pad to be much greater than the sum of its parts. The Ether Light’s combination of outstanding comfort, premium quality materials, and three-season versatility make it one of the most well-rounded options on the market, and one of the best choices for side sleepers to boot. 

Our main complaint with the Ether Light is that it delivers less warmth per dollar than many of the pads it competes with, but we also know that most campers limit their outdoor adventures between the spring and fall, which is where this pad really shines. If you don’t mind carrying a few extra ounces in the name of comfort, the Ether Light XT Insulated is a smart buy, especially if you happen to catch one on sale at your local outfitter. 

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