Interview – La Diagonale des Yvelines
Less than 40 km from Paris, La Diagonale des Yvelines (Diag 78) has established itself as a must-run event for anyone looking for a trail near Paris that combines nature, technical terrain, and a real sense of escape. This trail race in the Yvelines, easily accessible from Paris, attracts more runners every year who are searching for a true immersion in nature without leaving the Île-de-France region.
Between the forest trails of Rambouillet, the preserved landscapes of the Vaux de Cernay, and an organisation highly praised by the community, Diag 78 has become one of the top-rated trail races in the Paris region on TrailRunAdvisor.
But beyond the ratings, what truly sets this race apart is its human dimension — driven by passionate volunteers and a committed organisation. We spoke with the organising team to better understand the DNA of La Diagonale des Yvelines, the keys to its success, and its ambitions for the future.
Q1. La Diagonale des Yvelines is often described as a “true trail” in Île-de-France, with varied and technical courses. What would you say defines the race today?
We are fortunate to have in the Yvelines a rural and natural heritage of excellent quality. Sharing it with trail runners from different backgrounds also shows that just 40 km from Paris, it is possible to escape for the duration of a nature race.
All our volunteers, as well as the local municipalities and communities, come together year after year to help create this special day.
Q2. Many participants praise the quality of the organisation (course marking, aid stations, atmosphere, volunteers) as well as the beauty and diversity of the routes. What are, in your view, the key elements that make the experience stand out?
Everyone knows their role on race day. Course marking is handled by experienced trail runners, each responsible for securing around 10% of the route, from the lead runners to the sweepers.
Above all, our priority at every checkpoint, aid station, and start/finish area is to leave no trace of our passage — preserving the environment we live in is essential.
All our volunteers are genuinely committed, and many return every year. There’s a bit of the spirit of the 2024 Olympic Games in that sense.
Q3. In the Paris region, some iconic races like the EcoTrail de Paris attract large numbers of participants. How does La Diagonale des Yvelines position itself within this ecosystem, and what makes it unique?
Diag 78 is a human-scale race. Our limited number of race bibs allows us to stay close to the runners, and there are no points or restrictive requirements to register.
This race remains a human adventure.
Volunteers are often friends or family, and runners really feel that sense of closeness.
Q4. With record participation and very positive feedback, the race seems to have reached a new level. How do you explain this growing enthusiasm in recent years?
I’m not sure we’ve reached a new level, but we organise this race above all for the pleasure of sharing a great moment with runners and volunteers.
We aim to bring together what we believe is the best of our rural environment and heritage.
Q5. With a high number of reviews and an excellent average rating, La Diagonale des Yvelines is among the best-rated races on TrailRunAdvisor. How do you view this feedback? Is it a surprise or a reflection of what you’ve aimed to build from the start?
Our goal is runner satisfaction. Feedback has been taken into account since the very beginning of this adventure in 2019.
We regularly review comments across different platforms to challenge ourselves and improve whenever possible, within our means.
Q6. Runners often highlight the diversity of terrain: Rambouillet forests, Vaux de Cernay, the castle finish… How do you design the course to offer such a complete and immersive experience?
The route reflects what our region has to offer. It’s up to us to connect the most iconic locations, and access to certain private areas helps make the experience even more special.
Our objective is to bring something new every year. This involves extensive field reconnaissance, obtaining authorisations, ensuring the safety of runners and volunteers – in short, about a year of preparation.
Q7. What are your ambitions for the upcoming editions? Should we expect changes, or do you aim to preserve the current DNA of the race?
We want to remain natural, human, and focused on sharing and showcasing our environment. So for now, no major changes are planned — we want to keep things simple and accessible to all.
Conclusions
Today, La Diagonale des Yvelines confirms its place among the best trail races in Île-de-France, offering an experience that is both authentic, accessible, and immersive. As a true nature trail near Paris, it appeals both to experienced runners and those looking to discover trail running in a preserved environment.
In an increasingly crowded calendar of trail races around Paris, Diag 78 stands out thanks to its human-scale approach, respect for the environment, and high-quality organisation.
If you’re looking for a trail race in the Yvelines combining diverse terrain, a friendly atmosphere, and close proximity to Paris, La Diagonale des Yvelines is definitely one to add to your list.
