Sea to Summit UltraLight Insulated Mat

Features & Design

Sea to Summit’s multi-functional valve really stands out on the Ultralight. Lift just the top tab to inflate the mat, or lift the lower tab to open the entire hole and deflate quickly. I appreciated that the top tab of the valve has a one way valve behind the opening so that you can step away from blowing it up without losing any air. There is also a raised button in the middle of membrane that you can press to release small amounts of air for fine-tuning how firm the mat is, allowing you to easily adjust it to your sleeping preference.

The beauty in the design is that all of the features are incorporated into one valve, not multiple valves like some other mats.

(I liked the design of the valve so much that I also got two of Sea to Summits’ Aeros Pillows, which use the same valve design and are very comfortable.)

Sea to Summit Air Stream Pumpsack

I also have Sea to Summit’s Air Stream Pumpsack (a 20L dry sack that doubles as a mattress pump and only weighs 1.7oz), which allows you to quickly pump up the mattress without breathing in moist air. It only takes about 1 – 2 pumps with the Pumpsack to fully fill the sleeping mat. A big benefit of using the Pumpsack is that it keeps moisture from your breath from entering the mat, which can cause mold and mildew inside in the mat. Also, the Pumpsack makes a great dry sack for wet shoes or clothes.

Back to the UltraLight Insulated Mat…

This mat also features Sea to Summit’s “individual Air Sprung Cell” design with dot welding between each cell. Each “Air Sprung Cell” is an independent air chamber that conforms to your body’s contours, but doesn’t affect the adjacent cells. What this meant for me was that while this mat looked ultrathin and I worried that I was going to have another sleeping mat where my hip contacted the ground at night, it never did.

It also means that when you move around at night, the movement of your feet doesn’t make your head bounce and you don’t feel like you’re sleeping on a pool float. And when you roll to the side, the baffles don’t collapse along the edges. The mat feels very stable. I felt like I had better back support and a more comfortable night’s sleep on this mat than I ever did on my Alps Mountaineering Nimbus pad or my Therm-a-Rest self-inflating mat.

In order to add the warmth to this mat without adding weight, Sea to Summit uses an Exkin Platinum treatment on the outside and the Thermolite insulation on the inside of this mat. Exkin Platinum is a silver reflective layer deposited onto a soft, quiet, non-woven material which has been used in gloves and clothing before as a radiant heat layer. Its use in these mats makes them both warm and quiet. Unlike some other sleeping mats that make an annoying crinkly noise, this sleeping mat is super quiet.

The Thermolite insulation, is made with hollow-core fibers that trap in air for greater insulation and warmth without the weight. The fibers are engineered with a differentiated fiber shape which makes them approximately 22% lighter than round fibers of comparable diameter.

Deflating and Storing the Mat

Another beautiful detail of this sleeping mat is how easy it is to fold back into its stuff sack. The quick deflate valve at the top makes it very easy to roll up the mat from the foot without needing to squeeze out any excess trapped air before trying to fold it.

Once the valve has been pulled, it dumps about 90% of its air right away, and then the creases of where it was once folded before become apparent. So it is effortless to trifold the mat and roll it back up to the size of its stuff sack in a single go (the remaining air easily escapes from the open deflate valve while you’re rolling).

If you’re looking to go light and fast, this mat is for you. The design saved me a significant amount of time when trying to pack back up for an alpine start.

Value (and Comparisons)

The UltraLight Insulated Mats are a bit more expensive at $129 than other insulated mats on the market, but are well worth the price difference. For instance, the Klymit Insulated Static V sleeping pad (at 1lb 9oz, R-4.4) only costs $90, but is crinkly when you move at night, collapses at the edges if you roll over, and weighs over ½ pound more than the Sea to Summit Ultralight.

Therm-a-Rest’s NeoAir Venture WV (1lb 6oz, R-1.8) is much cheaper at $70, but weighs quite a bit more and is significantly less warm. Therm-a-Rest’s Evolite (at 1lb 1oz, R-2.1 $120) is closer in comparison for price to the Sea to Summit Ultralight, but is still a little bit heavier than, and not nearly as warm as, the Sea to Summit Ultralight (R-3.3).

Finally, there is Big Agnes’ Insulated Double Z (at 1lb 5oz, R-4.5), which will cost you slightly less at $110 and is warmer than the S2S Ultralight, but weighs 5.5oz more.

No other mat I’ve encountered has Sea to Summit’s multi-functional valve (a huge plus) or Air Sprung Cells (the closest thing to my mattress at home that I’ve slept on), and also provides the insulation of this mat.

Bottom Line

I’ve found the Sea to Summit UltraLight Insulated Mat to be very comfortable and very warm for its size and weight. I haven’t slept with it on snow yet, but my bet is that I’ll find it to be far warmer than my Alps Mountaineering inflatable mat, and more comfortable than any other mat I’ve used. I would opt for the Sea to Summit for the multi-functional valve and fast set up and break down alone.

Though it’s a bit pricier than some other options, the combination of weight, size, comfort, and R-value that the Sea to Summit UltraLight Insulated Sleeping Mat provides are hard to beat.