Sea to Summit Etherlight XT Extreme Sleeping Mat
'The best night's sleep you'll ever have in a tent is just one sleeping mat away'
Comfort & Shape
Storage & Packability
Wide range of shapes & sizes
10cm thick!!!!
Winter rated: R-value 6.2
Less than 1kg
Included pump sack
Still noisy

Kate introduced the Etherlight XT Extreme Sleeping Mat to us via email with the subject line ‘the best sleeping mat ever’. Here’s why she thinks so.


Last year, I bought my boyfriend a new winter sleeping mat. On its maiden voyage, we went snow camping, setting up just below the summit of Mount Twynam in Kosciuszko National Park. 

After a big day of touring with heavy packs on, and scoring a couple of turns, we were ready to pass out. Just as we lay down on our sleeping mat, Josh turned to me with a big grin across his face. ‘Kate, you’ve gotta try this.’ Smugly, I replied ‘Pfft, can’t be better than mine’. Josh persisted, ‘I’m not kidding, this is incredible’

Just like sardines, we rolled over each other in our sleeping bags and swapped mats. I turned to him with the same grin on my face. ‘Ohhh, you just made the biggest mistake of your life, there is no way you are getting this mat back tonight’

So whilst I lay on the comfiest sleeping mat ever, I jumped onto the Wild Earth website, using the very little phone service I had, and ordered another Sea to Summit ‘Etherlight XT Extreme Insulated Sleeping Mat’ for myself. It is THAT good.


The XT stands for extra thick and it does not disappoint. 10cm thick to be precise, it’s thicc! Using Air Spung Cell™ pattern (just like a pocket spring mattress), this design allows a more even dispersion of pressure across the mat’s surface, making it feel like a real mattress.

Due to these looped baffles, the mattress conforms to your body shape, making the it perfect for side sleepers like me, as the hips can rest into it without reaching the ground. Better yet, if one cell does burst, it’s not game over unlike the long baffles seen on other inflatable mats.



The Etherlight XT Extreme comes in three different shapes; regular, rectangular, and women’s.  The regular is a mummy shape; with rounded corners, its widest point is at the top then tapering towards the feet. The rectangular regular wide is self-explanatory, with an additional 10cm width to the regular shape. The women’s is advertised as a ‘women’s specific’ shape that’s wider at the hip and narrower at the shoulder, also with rounded corners.

This is the mat I have and my preferred shape out of the three as it gives me enough room to sleep on my side, without the additional weight of the rectangular wide shape. However, the women’s is also the shortest, with a length of 168cm. For me, as a tallish woman at 178cm, I opted for the women’s large. Each shape comes in both a regular and large, offering additional length and width at a small cost to pack weight.



An R-value (meaning resistance-value) is a rating of how effectively your sleeping mat resists heat loss. A higher R-value essentially means a warmer mat. For the Etherlight XT Extreme, all regular and rectangular-shaped mats have an R-value of 6.2, whilst all women’s sizes have an R-value of 6.3.

This makes it the perfect mat for snow camping, as heat lost to the colder, snow-packed ground is minimal. The mat is so well insulated, that my usual double mat technique for winter (inflatable + closed cell foam mat) is no longer necessary.



On the heavier side as far as regular sleeping mats come, this is still one of the lightest winter-rated sleeping mats around. The regular shape/size weighs in at 720g, whilst the women’s is slightly lighter due to its shorter length at 685g. The rectangular regular wide is the heaviest of the bunch, from the additional weight of width and corners, it weighs just under 1kg at 950g. For me, this is a small sacrifice to pack weight to have a cosy and comfortable sleep on and off the snow.


Sea to Summit boast that the 30/40D nylon face fabric is ‘quiet and grippy’, and in my honest opinion, I have never met a soundless sleeping mat. Yes, it is definitely less noisy than other mats, but if you really want a quiet night camping, inflatable mats just aren’t for you.

Storage Sack

The Etherlight XT Extreme rolls comfortably into the supplied storage bag with an integrated Airstream™ Pump Sack (included). At first, I thought these were a bit of a gimmick, but after using one they make your life so much easier, and extend the life of your mat.

They can be used in two ways; inflating with a single breath that fills up the entire sack, or by opening the bag and ‘catching the air’. They quickly fill up your mat in 2-3 cycles. This reduces the amount of moisture entering inside the mat, no to mention the Ultra-Fresh® anti-microbial treatment to further prevent mould growth within these inner layers.

Packed Size

This is the only drawback; the sleeping mat is bulky. Its packed size is around 17.5H x 17.5W x 24Lcm (regular & women’s). Roughly twice the size of a 1L Nalgene bottle, it’s on the larger size for inflatable mats. I’ve tried jamming it in various stuff sacks to minimise the size, but unfortunately due to the Thermolite® insulation, the supplied storage sack remains the best fit.


Added Bonus: PillowLock™ attachments

Most Sea to Summit mats now come with these clever little self-adhesive patches known as the PillowLock™ system. Compatible with Sea to Summit Aeros™ pillows, these patches stop your pillow from sliding around the mat all night. These are perfect for winter camping when you want your sleeping bag pulled right over your head to trap in heat, whilst still enjoying the comfort of a pillow beneath your head. 



Kate bought these mats with her own money for herself and her boyfriend. As a Wild Earth ambassador she receives a discount on products, but was not paid or endorsed by Wild Earth to write this article. She just really likes the damn mats.