Marathon des Sables

Marathon des SablesThe Marathon des Sables is the original desert foot race. It covers approximately 230km in the Moroccan desert, and each participant must carry his or her own rucksack containing food, sleeping bag and clothes. Participants enter as individuals or in teams of three.

For the Marathon des Sables, as with all desert ultra marathons, a balance needs to be struck. Running in the heat of the day, one wants the lightest load possible. On cold desert nights one wants to rest and sleep well. Desert nights can drop to a chilly 4°C, air frost temperature.


Down Sleeping Bag selection

Our race-tuned M.Degree K bags are ideal for the MdS. A range of temperature ratings allows you to select exactly the right bag for your metabolism, and carry no more weight than is absolutely necessary. If we made just one desert racing bag, it would be the M.Degree 200 K – with a Typical Operating Temperature of 4°C and a weight of just 340g. For those who want a little more comfort, the M Degree 250 K (0°C) at 390g is warmer. For those who sleep cold, there’s also the M.Degree 300 K (-3°C), and for those who get hot or who are looking for the ultimate weight saving, the 10°C M.Degree 100 K weighs just 240g.

For even more weight saving, consider a hoodless sleeping bag. The Delta Race 100 K and the Delta Race 200 K are the most extreme lightweight bags ever made, and combine with the buff or woolly hat you already have.

The M Degree 100 K and the Delta Race 100 K bags are really the preserve of the elite racer who’s prepared to rough it to gain the lightweight advantage – in a long, arduous event such as the MdS, the good night’s sleep gained from the warmer bags is a significant advantage in its own right.

The basic figures for the bags are:

Sleeping bag TOT (Min Temp) Weight Packed size
Hght x Diam (cm)
F gm oz 
M.Degree 100 K 10 50 240 8 21 x 13
M.Degree 200 K 4 39 340 12 21 x 13
M.Degree 250 K 0 32 390 14 21 x 13
M.Degree 300 K -3 26 445 16 21 x 13
Delta Race 100 K 10 50 200 7 18 x 10
Delta Race 200 K 4 36 300 11 21 x 13


Sleep System

Of course, it’s advisable to have an insulated top for chilly desert evenings and mornings, so an extremely lightweight option is to combine that top with our Desert Race Halfbag. This weighs just 240g and, when used along with our Ultra Pullover, creates a warm, flexible Sleep System with a TOT of 3°C.

  TOT (Min Temp) Weight Packed size
Hght x Diam (cm)
°C  °F gm oz 
Desert Race Half Bag 3 37 240 8 21 x 13
Ultra Pullover (with hood) -5/+3* 23/37* 260 9 10 x 18
Desert Race Half Bag/Ultra Pullover Combo 3 37 500 17  

* +3°C for sleeping in. Typical Operating Temperature when wearing during the day (when your movement / metabolism creates more heat than at night) is -5°C.

Additional points:

  1. TEMPERATURE RATING: Put simply these are the temperatures at which you should be able to get a night's sleep in normal circumstances. For fuller details about the TOT rating see this Technical Briefing.
  2. LINERS: A liner will add to the insulation if you choose the M.Degree° 100K or Delta Race 100 K but want more warmth. As always it is a trade-off between the extra weight and bulk and the warmth you gain (maybe 2°C). Silk liners at 140gm probably give the best value.
  3. FABRIC OPTIONS: These bags comes with superlight outer fabric as standard. Hypershell is a highly wind/water resistant optional outer, adding about 15gm to the total weight.
  4. ZIPS: Zips are an option on the M.Degree° K and Delta Race bags, but most competitors don’t ask for one. A short zip with a draught tube adds about 40g, a full zip and tube adds about 90g. There is also the option of a footzip which adds 10g and allows air to circulate around race-battered feet. As well as weight, zips add to the packed size.
  5. PACKED SIZE: PHD stuff sacs tend to be on the loose side. All these bags can be compressed further in your sac.
  6. Also available is our Desert Race Stuff Sac, equipped with multiple lashing points and formed into a slender shape to allow easy attachment to the outside of a full rucksack.

Down Clothing selection

Wafer Ultima clothing is especially suitable for desert racing: the Jacket is 185g, the Pullover is 155g and the Vest is only 115g. They’re small enough to fit in a pocket, but they’re rated to 0°C (about the warmth of a thick fleece).

Warmer than that is the Ultra Pullover mentioned above as part of the Sleep System. Even if not being used with a halfbag, it’s still a very useful top for cold nights when you are – inevitably – extremely tired and therefore feeling colder, providing sub-zero warmth at only 225g. Available as a jacket too. The sleeveless Ultra Vest provides the same level of insulation for the core, but tips the scales at just 150g.

The Minimus Down Pullover or Jacket are another suggestion for pairing with the Desert Race Half Bag. Slightly more featured than the Ultra Jacket and Pullover, with little weight penalty. Again, the sleeveless Minimus Vest provides the same level of insulation for the core, but tips the scales at just 205g.

The next Marathon des Sables starts on 4 April 2025.