The organisers of the Marathon des Sables claim it is the toughest foot race in the world.
And having sweltered here for the past couple of days and seen the punishing terrain, I can only agree.
They don’t call it a running race, because even the elite athletes that take this on, stop and walk parts of the route across the Sahara desert.
At times the course traverses mountainous sand dunes and rocky terrain that not even our 4 x 4 can tackle.
Into this cauldron of heat steps Duncan Slater: an Afghanistan veteran and double amputee. This is his second attempt to finish the equivalent of six marathons within six days in temperatures that can touch 50 degrees Celsius.
Walking on newly manufactured state of the art carbon fibre prostheses, he is determined this year he won’t be defeated by the desert.
Having chatted to him after the first day, he seems quietly confident and resolute.
He is humble, charming and tenacious. Focused not on his time, or on his position, but simply on taking this one kilometre at a time, for 250 km.
There are 1200 competitors here, about a third of them from Britain. Almost all are raising money for charity, and all have their own motivation and incredible stories to tell.
Duncan is fundraising for Walking with the Wounded, along with 23 other men and women taking part in the race. Together they are expected to raise tens of thousands of pounds for the charity.
Everyone here has to carry their food and sleeping kit on their backs. Typical packs weigh 10 -15 kg which means it’s army style rations and energy bars for all meals and little in the way of creature comforts.
Water is handed out at checkpoints along the route. It’s about as austere as it’s possible to imagine.
The scenery though is stunning. Great rippled landscapes of sand stretch for miles, punctuated by the odd oasis or dry riverbed.
It means Duncan and the others have hours and hours of time to think and talk; perhaps part of the attraction of this event for him.
He’s not only proving double amputees can do anything, but he is giving himself the chance to reflect on his injuries with his best friend Christopher ‘Paddy’ Moore who was with him in 2009 when their convoy hit an IED.
It is a mental and physical odyssey that if everything goes to plan will put Duncan Slater into the record books.
You can donate to Duncan's chosen charity, Walking with the Wounded, by visiting his fundraising page