Toughest desert marathons in the world

There are marathons, and then there are desert marathons. We take a look at some of the most extreme -- and beautiful -- foot races on the planet.

Started in 1986, the Marathon des Sables is held in southern Morocco's Sahara Desert. It covers 156 miles over six days... including the odd camel skeleton.

Describing itself as "The World's Toughest Foot Race," the Badwater Ultramarathon takes place in California's Death Valley at the height of summer, with temperatures often reaching 130F.
Competitors must race 135 miles nonstop, with previous winner Dean Karnazes calling it: "A midsummer inferno."

Following the ancient caravan route from East to West, the third Oman Desert Marathon will kick off this November, covering 102 miles in six stages.

Here, runners wind their way through Jordan's ancient city of Petra, with the option of a full or half marathon.

Australia's magnificent monolith, Uluru, looms in the background as competitors race across the country's red center. The next edition of the marathon will be held in July 2016.

The spectacular Atacama Crossing in Chile is one of four marathons held as part of the 4 Deserts Race challenge.
Those planning on completing all four races, must cover 621 miles, over 28 days, spread out across the year.

Also included in the 4 Deserts Race is a marathon across the Sahara, in Nambia. This individual race covers 155 miles, over seven days.

Runners also take on the Gobi March in China, as part of the challenge. Though it could just as easily be described as a climbing expedition, with the stunning Tian Shan Mountains as a backdrop.

There's no sand in sight, but Antarctica is still officially a desert, thanks to its lack of rain, lakes, and rivers. As such, it is one of the extreme landscapes included in the 4 Deserts Race.