A marathon

Sustainable, Ecological & Local

Since the first Cross du Mont-Blanc (1979), the Club des Sports of Chamonix work to offer great races while limiting their impact on the nevironment. Several actions have been put into place and still exist to this day.

Our approach

In order to reduce the environmental impact generated by our races, we try as much as possible to put our supply points near a water source, and in a place enabling the supply of electricity.

Bottles of water (plain and sparkling) have been suppressed from the supplypoints. The organisation have bought tanks (1000 litres). The technical staff have created a sparkling water with electrolytes. We serve this water with beer taps.

As an extension of this idea, the consumption of local products is obvious to us. Our cheese comes from the Montroc and Vallorcine farms.

When buying our products we give priority to those with minimalist packaging, bulk purchases, etc. to reduce our waste production.

We also limit administrative procedures on single-use paper, including the bibs delivery where the process is optimized to minimize paper consumption.

In collaboration with the SITOM (waste sorting center of the valley) the sorting of wastes is encouraged by an eco-collecting process especially in crowded places. Here, our teams of volunteers are very careful to this problematic (recovery of bottle caps for the construction of wheelchairs etc.)

Our teams of closers are in charge of cleaning all the trails after the runners’ passage.

In the order to limit the amount of cars during the event, we set up several shuttle systems.

  • The first one allowing to pick up and drive runners to their starting lines.
  • The second one allowing accompagnants to follow runners accross the valley without using personnal car.

The frequency of shuttles has been optimized in order to reach our guests’ expectations.

Following the idea of reducing vehicle use, members of the organization have access to a fleet of electric bicycles that they use as much as possible.

During races, runners as well as the public of crowded areas have access to composting toilet which produce only biodegradable waste.

Several measures are still discussed and we will not fail to keep you informed of their future achievements.



This year, the organisation decided to calculate the carbon footprint of the event and confirmed that the major part in the greenhouse gas emission was transportation of the runners. We offer the runners  who decided to come by plane, car or bus the possibility to donate money for an environmental project in order to offset their emissions. From their registration to right before the race, they can make a donation.

It is a success because more than 2000 runners have donated money, for a total of 5000€. The Club des Sports commits to give all the money to environmental causes.

After long research, we have selected two associations whose projects are pertinents and in line with the Marathon values :

The natural reserve

of aiguilles rouges

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A part of the races of Mont-Blanc Marathon cross the wildlife park of the Aiguilles Rouges, an emblematic place which is protected by the Community of Municipalities of the valley of Chamonix Mont-Blanc since 1972.

These are the parts of the route which cross the wildlife park :

On the Mont-Blanc 23km:

On your way from Montroc to La Flégère you will cross a small part of the wildlife park where fir trees offer some shade before coming out of the Bois de la Trappe.

On the Mont-Blanc 42km:

You will follow a part of the botanical trail from the top the pass of Col des Montets all the way down to Trélechamp. Small signs indicate the names of the most remarkable flowers that thrive there. 
At the top of the pass, at the back of the chalet, several ibexes have taken up residence (if you are lucky, maybe you will see them). While going up to the Aiguillette des Posettes, you will cross the wildlife park (a sign will indicated it)  This area is the home of mountain goats and wild boar. There is a place called “Les Ardoisières”, an eagle area. Don’t lift your nose but look at your feet !

On the Mont-Blanc 90km

You will enter in the wildlife  park after going through the food supplies of Flégère until the Col des Montets. On this part of the trail you will might meet many ibexes of the Alps, thank you to respect them.

Thank you to protect the wildlife park by not throwing any garbage and by staying on the marked path.



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 Marathon Clips 

Réalisation : Cybergraph – 2023.