Sea To Summit UL Insulated Sleeping Mat | Review - Outdoors Magic

Outdoors Gear, Equipment, News, Reviews, Forums, Walking Routes and More at


Sleeping Bags

Sea To Summit UL Insulated Sleeping Mat | Review

Comfortable, packable, easy to manage and lightweight, there’s a lot to like about this mat from Sea to Summit

Why We Chose The Sea to Summit UL Insulated: Excellent warmth-to-weight, very comfy, quick to inflate and deflate

The fact that this mat still remains one of the most innovative out there even though its a few years old now says quite a lot. After all, the world of sleeping mat tech is surprisingly fast moving.

You just need to look at the images here to see how it’s different. Rather than your standard sleeping mat which has horizontal or lilo-like vertical baffles, this uses air sprung cells which, as we’ve found through testing, create as close to a bed mattress feel as we’ve seen, and all at just the meagre weight of 480g (regular size).

Who Is The Sea To Summit Ultralight Insulated For?

With its R-Value (basically the temperature rating) of 3.3 combined with its light weight and packability this is the kind of mat that should particularly suit any backpackers who are happy to venture out from the early stages of spring right through to the later stages of autumn. It would even suit some of the milder nights we get in winter here in the UK.

Materials and Construction

A 40D ripstop nylon is used throughout. This has a very lightweight and slightly fragile feel to it so you will want to take a bit of care to ensure you don’t puncture it on any rough ground or, say, if you’re bushwacking while it’s strapped to the outside of your pack. Still, with the protection of a groundmat or bivy bag, you shouldn’t have any trouble.

“I’d give this 9/10 for comfort.”

The benefits of the air sprung cells are instantly noticeable when you lie on the mat; they essentially deform individually and in turn conform to your exact body shape, elevating even your hips and shoulders off the ground when you’re lying on your side. The overall height is 5cm, which is fairly generous. For comparison, Therm-a-rest’s NeoAir Xtherm offers 4cm while Nemo’s Tensor provides a whopping 7cm.

As for the insulation, that comes from the combination of two of Sea to Summit’s technologies. The first, Thermolite, involves specially-designed lofting fibres that are located within the 200 cells throughout the mat. The second is something called Exkin Platinum, which is essentially a super thin metalised layer that reflects radiant heat loss back to the user. More on this in the Tester’s Verdict below.


We tested the regular version which measures 183 x 55cm when inflated. You can also find this in XS, S and L sizes as well. Something for everyone then.

The Sea to Summit UL Insulated features air sprung cells which mould to the contours of your body. Photo: Mike Brindley
A neat and convenient bundle when packed up. Photo: Mike Brindley
A two-way valve that allows quick and easy inflation and deflation. Photo: Mike Brindley

Packed away in its stuff sack, the regular measures 10cm in diameter and 23cm in length. Not the smallest out there then but still very, very packable. In other words, you’ll barely notice it in your pack.

Inflation and Deflation

The valve on the Ultralight Insulated is one of those things that comes across as simple but only because it’s so well designed. One of the best things about it is that it’s flat, so you’re unlikely to damage it if you kneel or step on it by accident. As it’s one-way you can blow into it and move your lips away without air escaping and to deflate it you can either do this gradually (say, if you decide in the middle of the night that you want a softer sleep) or instantly by flicking the whole thing open.

What about the inflation process then? You can either do this by blowing straight into the valve, which doesn’t take too long or require much effort or you can use the stuff sack that it comes in as a pump bag. For this, all you need to do is pop it into the valve, blow one single breathe into the other end (without your lips needing to touch the sides) and then roll up the fabric to transfer the air. Thanks to this, we’ve found the mat can go from in its stuff sack to ready to sleep on in less than two minutes.

Tester’s Verdict

Will Renwick, editor of Outdoors Magic

“I managed to sneak out with this for a quick wild camping in the south east of England just before lockdown kicked in in Britain and from what I saw I liked. First up, the process of inflation really is super quick and requires very little effort. Thanks to that pump sack and the clever Bernoulli principle it uses, it really does just take no more than a puff or two to have this up and ready to run. Packing it away is also easy, you just open up that quick valve, fold it a couple of times widthways and then roll it up from the feet lengthways.

“It really does just take no more than two puffs to have this up and ready to run.”

“I’d give this 9/10 for comfort. It’s not glamping/car camping mat levels but it’s as good as they get for lightweight backpacking mats. The Nemo Tensor, which is much bigger and heavier, probably gets my top spot for comfort levels, however this mat comes in second and probably trumps Nemo with all elements considered. The regular version was definitely the right size for my 5 foot 10 height and 11ish stone weight. I think I’d probably be fine with the Small length as well.

“During a cold March night where the temperature must’ve dropped to about 4C, I didn’t feel any discomfort or cold spots, so the insulating layer must’ve done its job.

“There seems to be a bit of debate online about how quiet this mat is. Sea to Summit claim it provides a peaceful night’s sleep but there are a few reviews that say they found it a touch noisy. In all honesty, mat noises don’t disturb my sleep much (whether their from my mat or from someone on one beside me) and I certainly didn’t have any problems when testing this. From what I can tell, any noise will likely come from your own sleeping bag fabric swishing on the mat’s fabric but that certainly won’t be loud.

“It’s unfortunately too early for me to comment too much on durability however I will say that I would be wary of using this on any rough stuff. It is handy that it comes with a repair kit with six patches though – just for that peace of mind.”

Sea to Summit UL Insulated

Newsletter Terms & Conditions

Please enter your email so we can keep you updated with news, features and the latest offers. If you are not interested you can unsubscribe at any time. We will never sell your data and you'll only get messages from us and our partners whose products and services we think you'll enjoy.

Read our full Privacy Policy as well as Terms & Conditions.