"...When I first unravelled it at base camp my team mates laughed at how ineffective this pumping system seemed to be. This turned out to be an illusion however, because after only a few minutes they were all suffering serious envy as the inflatable mats they'd previously considered luxury looked a little underfed next to my behemoth...

The Exped DownMat 7 Pump is marketed as a super comfy inflatable mattress, which is considerably warmer than a standard air mattress because its chambers are partially filled with down. I took one on a recent trip to Patagonia to test it out.

The first thing I discovered was that the DownMat employs a curious but very effective built-in pump system: you simply cover a hole with the palm of your hand and depress the foam, then remove your hand for the 'pump' to re-inflate. When I unravelled it at base camp my team mates laughed at how ineffective this pumping system seemed to be. This turned out to be an illusion however, because after only a few minutes they were all suffering serious envy as the inflatable mats they'd previously considered luxury looked a little underfed next to my behemoth.

Exped's Andy Brun gives tips on inflating Exped DownMats

In terms of comfort, the DownMat surpassed anything I've ever slept on before, and it was also very warm. There are now quite a few 'fat' inflatable mattresses on the market, and it is useful to compare them on both weight and insulation value. For example the new Thermarest 'Neoair' range looks like it might rival the DownMat for comfort, and they certainly beat it for weight, but they aren't nearly as warm; the Neoair has an R value (a measure of thermal resistance) of 2.5 compared to the DownMat R value of 5.9.

The theory goes that if you can substantially reduce the heat loss to the ground you can get away with carrying a smaller sleeping bag. The extent to which this theory can be applied depends on the relative temperatures of the air and the ground; the conditions that best favour a beefier than usual mat but a lighter than usual sleeping bag being sleeping for many nights on snow or ice, when heat loss to the ground is greatest.

The DownMat, at 880g for the 6-foot version, is heavier than either the Neoair (410g in the same length) or a typical closed cell foam mat (also 410g), so if making a trade-off for a lighter sleeping bag isn't really an option, then it will feel like a bit of a heavyweight. When faced with the prospect of carrying it for 6 days around the Patagonian icecap, I chose to forego its extra warmth and comfort for the lighter weight offered by a closed-cell-foam mat.

However, the materials the Exped mat is made of feel like they will last, so in addition to being a good choice for many days sleeping on snow, it will work very well in situations where you'd be sleeping on it a lot, and carrying it a little; for example as a car camping mat, or for use at a basecamp.

Exped DownMat 7 Pump

• Light foam blocks at the mat's ends prevent down escaping.
• Durable, airtight and humidity resistant laminated polyester fabric.
• Brushed polyester top surface is slip resistant and comfortable.
• Dark colors dry quickly.
• Seams are high frequency welded for durability.
• Loops can secure the packsack to the mat when used as a pillow.
• Low profile valves (one for inflation and the other for deflation) ensure ease of use.
• Valves are flat so are protected and durable.
• Thick air cushion provides comfort and smooths out uneven ground.
• As down compresses extremely well, DownMats packs smaller than other insulated mats.
• Exped only uses IDFL-certified goose down, treated to eliminate the effects of humidity.
• Temperature: -24°C
• Sizes: short 120x52x7cm; regular 183x52x7cm; DLX 197x65x7cm
• Packed sizes: 23x12cm; 23x16cm; 27x14cm
• Weights: 630g; 880g; 1140g
• Fill Weights: 130g; 170g; 220g

Besides its weight (which is not excessive, just considerably more than a lightweight inflatable or closed cell foam mat), I only identified two problems with this Exped DownMat. The first is that if you are trying to use it with a Partner as opposed to a partner then you'd better make sure you both have one since trying to cuddle up is difficult when one mat is half a foot thicker than the other. The second is that the mat occasionally makes a noise resembling an embarrassing bodily function as you shift on it in a tent. That was my excuse anyway.

What Exped say about their down fill

Heat loss is dramatically reduced with down insulation inside the mat, as demonstrated by EMPA, the Swiss Federal Labaratories for Materials Testing and Research, and field tests by expeditions. The thick cushion of air also provides comfort and smooths out uneven ground. And, as down compresses extremely well, DownMats packs smaller than other insulated mats.

Light and warm: The DownMat 7 Pump has a R-Value of 5.9. At about the same weight a standard 2.5cm self-inflating mat only has a R-Value of 2.5. Further EMPA tests demonstrated that regular mats lose 3x more heat to cold ground than to the air. The conclusion: use a lighter weight sleeping bag with a DownMat to achieve consistent overall comfort, and still reduce weight and bulk!

Exped only uses IDFL-certified goose down, specially treated to eliminate the effects of humidity that may reach the mat's interior.

PRICE £115

• More information on the Exped Website

About Es Tresidder

Es Tresidder is an alpinist, mountain runner and environmentalist. He lives a semi-nomadic lifestyle, travelling between mountain regions to climb and run while studying for an MSc and earning a crust as an environmental building consultant wherever he can get an internet connection.

Es supplements this with lectures about his climbing and running. He is currently the record holder for running the Cuillin ridge on Skye, and climbs and runs to a high level in a variety of disciplines.

Es is currently in the Pyrenees representing the UK in the ski mountaineering World Championships.

His personal webpage is: Es On Ice

You can find out more about his environmental consultancy at leangreenconsulting.co.uk