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Extensively tested and reviewed by Cairngorm Treks from May to September in the Cairngorms, Glen Affric, and surrounding mountainous areas.

Rest and recovery! An important factor for anyone who spends a great deal of time in the outdoors. Whether your adventure is on land, water, two wheels, or climbing a rock face - if you intend to spend multiple days in the wilderness it is essential to pack smart and give yourself time for recovery. This can often only be for a few hours at a time so choosing a sleep system that's personal to you is essential. In Scotland, it's not uncommon to camp in or around minus temperatures for most of the year, so a suitable sleeping bag paired with a ground mat takes pride in our pack during every season.

Sea to Summit have what appears to be a very interesting lineup of new sleep systems for 2019. The range is varied to suit all activities with a complete system including a mat, bag, pillow, and liner. Nothing has been left out and many might say that this is airing on the side of luxury. We were after a sleep system aimed at high camping in Scotland throughout the warmer months. For this, we require a set-up that should be comfortable right down to around 0 degrees, and will be light and packable. There are lots of fantastic modern systems that suit these requirements so we were eager to see how the new systems from Sea to Summit would hold up. 

Here is a list and a bit of info surrounding each item we received:

Sea to Summit Spark SPII Sleeping Bag

• -2°C Comfort Limit, 300g of 850+ Fill Power ULTRA-DRY Down, Weighs 506g in a regular size.
• Materials
• Insulation: RDS 850+ Loft Premium Goose ULTRA-DRY Down
• Shell: Ultralight 10D Nylon Shell
• Zipper: Left-side #3 YKK zipper
• Comes with: Ultra-Sil™ compression bag and storage cell

EN ratings for sleeping bags can often leave us confused with many factors contributing to whether a bag is suitable for a user. Many companies now adopt a bit of blurb along with the EN ratings to give a better understanding of what to expect. Sea to Summit described the lower limit of the Spark SPII as stated here. “The temperature at which a standard man can sleep for eight hours in a curled position without waking. If you consider yourself a warm sleeper, use this rating to decide the coldest temperature the sleeping bag is suitable for.” This is then a perfect description for our guide Myrddin who sleeps at the warmer end of the scale. If you sleep colder, then it would be wise to look at one of their slightly beefier options.

We were a bit dubious at first when we received the Spark SPII. The storage cell it arrived in gave us a bit of concern, as for a bag with a comfort limit of -2 there didn't appear to be much actual bag to hold. What did restore our faith was just how much the Spark SPII lofts once given the chance to expand. The Ultralight 7D and 10D fabric combined with 850+ Loft Premium Goose Ultra-Dry Down certainly keeps weight and bulk to a minimum. Once lofted it takes a whole new appearance and for such a thin denier of fabric it is surprisingly robust and also very comfortable. The classic contoured mummy shape is a tried and tested winner and feels supportive and well-fitting to the body, plenty of movement without feeling constricted. Although with our reviewer at 5ft 8in tall, users will find the regular size to be a bit on the tight side and it would be wise to purchase the larger version. Extra down has been added to the torso area in the form of vertical baffles. This is to add warmth to the core whilst also mitigating the movement of down throughout sleep otherwise creating cold spots. A half-size zipper provides ample room to get inside, whilst the usual additions of draft tubes and collar means that the Spark SPII hasn't lost any functionality in favour of weight saving. All in all, this is a very impressive bag considering the overall weight and packability.

Sea to Summit Ether Light XT Insulated Mat

• R-Value: 3.8
• Dimensions: 183 x 55 x 10cm
• Packed Size: 12 x 24cm
• Weight: 425g

The Ether Light XT certainly sparked a bit of interest. The packaging is packed full of detail and promises this to be more than just another air-mat. Out of its packaging, it is notably larger compared to its competitors, although at 425 grams it's still light for a mat with an R-Value rating of 3.8. A multi-functional storage sac doubles as an inflation aid with a sturdy valve to connect to the mat itself and also, if reversed, will blow up the pillow too. It's a simple and decent design, keeping everything compact and ready for use. Ultra-Fresh anti-microbial treatment is added to the TPU formula to prevent internal mould growth which can degrade the insulating properties of a mat.

Once fully inflated the very large 10cm loop baffle Air Sprung Cells are a move away from the usual tube-type formation found with most other brands. The extra bulk of the Ether Light XT further redeems itself as the dimensions offer a wider mat than we are used to, for us this is a step in the right direction and offers an abundance of support and comfort. Exkin Platinum and Thermolite are used for insulation to give it a high 3.8 R-Value. 30/40D Nylon fabric make for a tough outer and although there is a bit of a rustle to the Ether Light XT once inflated, it’s fairly quiet compared to similar types of mat as it utilises synthetic insulation alongside a reflective barrier, which shouldn't disturb a neighbouring camper.

The PillowLock system as advertised on the side of the packaging appeared a bit underwhelming. We searched the box for this high-tech solution for keeping your pillow locked in place only to find a small bag containing 4 pieces of Velcro. It has to be said though, that simple is usually better especially considering outdoor gear, and we will give the PillowLock system a fair run out.

Sea to Summit Aeros Ultralight Pillow

Weighs: 56g (excluding pouch)

Materials: 20D laminated polyester

Sea to Summit are certainly treating us here. Many may see the addition of a pillow as unnecessary added weight, with a dry bag filled with spare clothing usually providing a decent solution. In most cases we would agree but at a mere 56 grams and the chance to use the PillowLock system we were intrigued to see how the complete sleep system performed as a unit.

The Aeros is minute in size, not much bigger than a satsuma. Although small in size the high strength TPU used throughout makes for a well-built piece of kit. It has a slightly smaller multifunctional valve compared with the Ether Light XT which can also be inflated if you reverse the pump sac. We really like this simple and effective design which shows the attention to detail made throughout the sleep system.

Sea to Summit Silk Stretch Liner

• Weighs 112g

We use silk liners on all of our multi-day treks. They are a great option for keeping your sleeping bag in good condition whilst also adding a layer of comfort and in some regards an extra layer of warmth. The Silk Stretch liner has the same premium feel like their usual silk liners but also has a stretch panel located on each side. This is something new that we have never used before so it will be interesting to see if there are any noticeable differences. 

The first area to note is just how compact and light this system is. A combined weight of under 1200 grams is very impressive, we remember not too many years ago regularly packing in a sleeping bag alone of around this weight. All together this system is super packable. So much so that we have spent multiple days away in the hills using just a lightweight 33L pack including a lightweight shelter, 3 days of food, stove, extra layers, and all safety equipment required from a guide.

Using this system from May through to September we can honestly say we never had a cold or uncomfortable night’s sleep. In May we were a bit caught out with a late snowfall high camping on the Mullardochs. We would of never known that the temperature outside the tent fell to -2 degrees with the Sea to Summit sleep system keeping us toasty warm. It was only upon waking in the morning that we noticed a dusting of snow on the ground.

Although each item plays its part, the standout performer is undoubtedly the Ether Light XT mat. The increased width and depth provided outstanding comfort and the Air Sprung Cells just add to this keeping you in place throughout the night. Our guide Myrddin found this to be a great option if you’re a side sleeper, adding that the easy-adjust valve made simple work of finding that sweet spot. Although the valves are a simple and effective solution the pump sac itself is a bit on the small side and not as efficient as compared to other brands. To help fill, the guidelines state you must blow into the sac. We had always been under the impression that any moisture that would be present in your breath would then work its way inside your mat and over time would damage the thermal qualities. We can only assume the antimicrobial treatment would prevent this issue.

A common problem you come across whilst discussing air mats are the noise/rustles you can encounter as someone is moving around. Although the Ether Light XT is not guilt free of this it is noticeably quieter compared to most.

It is certainly not an air mat that lets much unwanted cold penetrate through. For conditions outside of winter, an R-valve rating of around 4.0 is the best for balancing a thermal rating between a mat and a sleeping bag’s stated rating.The combination between the Ether Light XT and the Spark SPII meant even sleeping in temperatures down to just below freezing we were within the stated lower comfort limit of the Spark SPII and feeling suitably warm.

The Spark SPII certainly packs down small into the included stuff sack and is one of the most impressive weight-to-warmth ratio sleeping bags we have ever used. The Ultralight 10D Nylon Shell is almost see-through in appearance but does not feel as delicate as it may appear. It’s definitely not going to be the type of bag you would like to bash around a rock face or sleep directly on the ground with, but inside a shelter or bivy, treated with a bit of respect, it won’t give you much concern. Once given enough time to loft the Spark SPII starts to really impress. The 850+ Fill Power Premium Goose Ultra-Dry Down is super soft and a pleasure to sleep in. Sewn through horizontal baffles are used to minimise weight, whilst vertical baffles around the chest with increased goose down keep the core areas warm. We like this approach and found it offers a good balance of warmth throughout most areas. Although a touch more down added around the foot box particularly would be beneficial as this was an area where cold spots started to develop, but only on very cold nights.

The hood and neck baffles are simple in design and keep vital body heat trapped inside. The ½ length YKK zipper can be opened to allow extra ventilation when needed. It does need to be noted that the zipper is difficult to open from the inside. Many a morning we spent battling to free ourselves. We have read reports that other users have found it to be snag free and easy to use. In our experience, this was not the case.

The Aeros Ultralight Pillow packs into a tiny sac and can fit inside the storage bag for the Ether Light XT, keeping everything nicely together. It’s very simple in design and uses the same style of valve as with the Ether Light XT. It may take a bit of time to adjust the firmness to an individual’s liking but for an air pillow, it’s a rather comfortable one. The PillowLock system that holds the Aeros to the Ether Light XT is a simple design but works surprisingly well. We take back the initial sniggers and can only applaud Sea to Summit for taking this simple approach, as many brands have tried a more complicated approach which has almost always failed.

We are not too sure if the Sea to Summit Silk Stretch Liner makes a massive difference compared to a regular silk liner. What can be said is it’s just as comfortable, and certainly waking up in the morning hasn’t resulted in a cocooned tangled state around the body. It’s also very easy to clean and essentially prolongs the life of your sleeping bag. This is especially important in regards to the Spark SPII with its 7D internal lining. It also has its own included stuff sac but to save weight and keep the sleep system together we placed it into the pocket of the Spark SPII.

Our Verdict

Choosing a sleep system that works is a personal experience which will incorporate many factors. Many brands have now adopted the addition of a short description to accompany their intended EN ratings and this is a great improvement. For us, the Sea to Summit system used in this review was perfect for someone who sleeps warm, wants to pack small and light and is intending to sleep in the Scottish mountains outside of winter. The system packs down well and weighs under 1200 grams including the air mat, sleeping bag, pillow and silk liner. As a collective, it is impressively low in bulk without sacrificing warmth or comfort. The system is adaptable as you can add a thicker liner, wear an extra layer or purchase a heftier bag with enhanced thermal qualities, but an area which we found irreplaceable was the Ether Light XT. It’s the standout performer and can be combined with many different sleeping bags and will always retain a high standard of comfort and warmth. The extra bulk is worth the space and can be easily saved elsewhere with a reduction in size of a sleeping bag. We did try the Spark SPII with separate air mats of varying R-Valve rating, but none complimented the thermal ratings of the Spark SPII as closely as the Ether Light XT. The PillowLock, although simple, is a great design and works well if you are a fan of air pillows. Obviously, like with all products, there are a few downfalls. The pump sac could be better, the zipper caused a few issues and the stretch liner didn’t appear to show as much innovation as we had maybe been looking for but overall Sea to Summit have created a sleep system which provided excellent rest and recovery and was a pleasure to use. There are also many other options to choose from, so it would be well worth looking online to find a Sea to Summit sleep system that would suit your needs.