“It's all about discovering new places and nurturing your curiosity”

Let’s start with your most recent achievement: setting a new women’s world record in rebreather diving. How did you become interested in this sport?

It all started at EPFL. I was already a big fan of snorkeling, and during the first year of my physics degree, in 2008, I took part in a summer camp offered by the UNIL-EPFL sports center. There I fell in love with diving and obtained my Level 1 diving certificate in Saint Tropez.

After that, I took advantage of the school breaks to go diving and obtain progressively higher certifications. I also traveled a lot during my PhD, including to countries known for their excellent diving opportunities, like South Africa and Brazil.

What prompted you to aim for a new world record?

Over the years I moved into what’s known as technical diving, or diving at high depths. What really motivated me was the prospect of venturing into undiscovered areas. I was intrigued by underwater shipwrecks in particular. I’ve explored the remains of an oil tanker off the coast of Genoa several times, for example, and have often been diving near Marseille, where there are a lot of fascinating wrecks, especially from World War II: boats, airplanes and even a submarine.

After completing dives of over two hours and reaching depths of more than 80 meters, I eventually wanted to go further. I looked up the existing world records out of curiosity and saw that the women’s record for rebreather diving was 198 meters. I felt I could definitely reach the 200-meter mark. But finding the right location to do that wasn’t easy – there aren’t a lot of places where you can dive below 200 meters. In the end I chose the Cassidaigne canyon, an oceanic trench off the coast of Cassis in southern France.

I began taking part in scouting workshops for French national teams. I was selected for the national juniors 4-way team and then, in 2018, the national 4-way and 8-way teams. Formation skydiving is when you freefall on your stomach while holding onto your team members, and arranging yourselves into geometric patterns. The training was really intense – we carried out around 600 jumps each year.

The dive when you set your 222-meter record, on 30 September 2024, lasted four and a half hours. What was that experience like, and what was going through your mind?

The descent went very quickly – only 14 minutes. There’s no real limit on how fast you can descend, you just have to be careful about the pressure in your ears, for instance. I reached the bottom of Cassis bay, which sits 120 meters below the surface, and then kept going along the ocean floor out into the trench. I eventually reached a depth of 222 meters – the goal I’d set myself. It was extremely dark in the trench, but that took nothing away from the thrill of exploring a place where nobody else had probably ever been. I even saw a sandy dogfish, which is a kind of shark.

The most difficult part was the ascent. There aren’t yet any established decompression stops at that depth, and you have to rise slowly to prevent decompression sickness. I used computer software to help me adjust my speed. I also had to constantly make sure the rebreather was working correctly. Rebreathers have many advantages over cylinders – they offer up to six hours of dive time and are silent and don’t cause bubbles, which means you can go more unnoticed as you explore marine life. But they’re more complicated technically because they work in a closed-loop system, essentially recycling the air you exhale. So you have to keep a close eye on the oxygen levels and pay attention to physiological signs of high CO₂ concentration in the loop.

It was only when I had ascended to 100 meters that I started to relax a little. At that point I knew the hardest part was over. I began the decompression stops at 80 meters. The first ones lasted just a few minutes and then got progressively longer. I spent one hour and 40 minutes at the last one, just six meters below the boat. I removed the equipment I no longer needed and had something to eat and drink. I even started watching a movie – Denis Villeneuve’s Dune – to pass the time. It was surreal to see people moving around in a parched desert landscape while I was surrounded by water!

How did things change after you became a world record-setter?

I was contacted by a number of journalists and received invitations from several diving clubs. I also started giving talks on my experience, including at the international diving conference in Paris this past January. Women in particular were happy to learn about the record. And a handful of hyperbaric physicians – that is, doctors who study the medical use of high-pressure oxygen – asked about the technical aspects of the record-setting dive.

You mention the positive feedback you received from women. Was the prospect of serving as a role model also something that propelled you to set a new record?

Yes, that was definitely part of my goal. I wanted to show there’s no real reason for the large gap between women and men, who have completed dives of over 300 meters. The gap merely reflects the fact that fewer women are interested in the sport – we account for just 13% of the people who practice technical diving. I’m often the only woman on the boat, just like I was sometimes the only woman in my classes at EPFL.

I wanted to show there’s no real reason for the large gap between women and men, who have completed dives of over 300 meters. The gap merely reflects the fact that fewer women are interested in the sport – we account for just 13% of the people who practice technical diving.

You’re also an outstanding formation skydiver – three-time world vice champion and several-time French champion, and you’ve won a World Cup.

Skydiving is another sport I started at EPFL, and in the same year as scuba diving! A friend told me about how much he enjoyed freefall, and I was curious to try it myself. I completed my first jump in July 2008, just a few months after my first underwater dive. During my second jump I wondered what I’d gotten myself into. But I soon began to enjoy skydiving and was hooked by the end of the summer.

How did you get from there to the top of the sport?

The path was a little like for deep sea diving, in that I spent my weekends and school breaks practicing. I took over as head of the skydiving section of Aéropoly – the EPFL student club for aerospace enthusiasts – shortly after that first summer. When I was in Paris for my PhD, I joined a formation skydiving club and began taking part in scouting workshops for French national teams. I was selected for the national juniors 4-way team and then, in 2018, the national 4-way and 8-way teams. Formation skydiving is when you freefall on your stomach while holding onto your team members, arranging yourselves into geometric patterns. The training was really intense – we carried out around 600 jumps each year. Skydiving is recognized as a high-level sport in France and athletes are supported by the French Skydiving Federation. That provides a lot of structure as well as equipment and much-needed financial assistance, because it’s an expensive sport.

What was your most unforgettable skydiving experience?

Winning at my first World Cup in Arizona in 2019, and especially the last jump I made during that competition. Each team has to make ten jumps in skydiving competitions. In Arizona, we were well-placed enough after the ninth jump that it was pretty clear we would win.

When our team separated to deploy our parachutes at the end of the tenth jump, it suddenly dawned on me that we’d just won the World Cup – and this during my very first international competition. Until then I was too concentrated to genuinely realize what we’d achieved. Usually, when you descend with your parachute open, you try to reach the ground pretty quickly. But that day I took the time to really enjoy the moment and the view, in the middle of the desert.

You mentioned that skydiving can be costly – deep sea diving is also an expensive sport. How are you able to finance both these activities?

It isn’t always easy. For the diving, I had the support of organizations that lent me the necessary equipment, including a prototype underwater scooter that allowed me to reach great depths and the boat I used for the record-setting dive. In addition, CNES, my employer, provided some of the funding. But most of the money came out of my own pocket, which I realize can be a big hurdle for many.

Alongside your sporting activities, you also have a demanding job at CNES. What’s your role there?

After I graduated from EPFL, I obtained a PhD in astrophysics from the Institute of Theoretical Physics at CEA Paris-Saclay. I was soon drawn to space engineering and joined CNES in 2018, in Toulouse. Right now I’m working on two main space missions, both of which are international in scope.

The first is Dragonfly – a NASA mission focused on Titan, which is Saturn’s largest moon. The main goals are to determine if conditions are suitable for microbial life and to examine the prebiotic chemistry. Data from this mission could provide valuable insights into how life is formed and the chemicals that were present when the solar system was created. CNES’s role in Dragonfly is to support laboratories building a gas chromatographer.

The second mission is Ariel – a European Space Agency mission to study the atmosphere on exoplanets, or planets outside our solar system. At CNES, we’re contributing in the development of an infrared spectrometer for analyzing chemical compositions. Ariel actually ties back to my time at EPFL: as part of my master’s project in space technology, I worked on Cheops, an exoplanet research mission that Ariel is derived from.

The things I’m interested in are sometimes described as ’extreme,’ but that’s not what draws me to them. It’s more the excitement of venturing into new places and learning new things.

Did you already plan to pursue a career in astrophysics before going to EPFL?

Yes. I’ve been fascinated by outer space and curious about the universe ever since I was a child. During my master’s at EPFL, I focused mainly on understanding the theory through specializations in cosmology and particle physics. For my PhD, I studied the theory of dark matter. I moved into applied astrophysics later on.

How do you manage to juggle a job as a space engineer along with two high-level sports?

It’s not easy – it requires a lot of planning ahead. It’s similar to what I do for project management: I set up a timeline and detailed schedule so that I can reach my objectives in each area on time.

At the start of each year I map out my job commitments, such as speaking at a conference or working on a satellite integration. When I was on the French formation skydiving team, we were given yearly schedules of our training sessions and competitions, which helped me plan things out. Then I fit my diving weekends in whenever I could.

I still use the same full-year approach. But since I’m no longer on the French national team, my schedule is a little more flexible. Now I give more priority to diving.

What would you say your different interests have in common?

I’ve always been interested in sports – I ran track and did horseback riding when I was little, for example. But I wasn’t very brave when I was young. My parents were undoubtedly surprised to see me take up skydiving and deep sea diving!

It’s all about discovering new places and nurturing your curiosity. The things I’m interested in are sometimes described as “extreme,” but that’s not what draws me to them. It’s more the excitement of venturing into new places and learning new things. All my interests involve environments where humans generally aren’t meant to be, but which technology now lets us explore.

Now that you’ve set a world record, what’s next?

There are so many things I want to do, it’s hard to pick! I’d like to do more wreck diving, which I find increasingly interesting. When I set the diving record I didn’t have any other goals in mind, but now that I know it’s feasible to descend to 200 meters – and have found a decompression profile that works for me – I’d like to explore wrecks at this depth. It’ll take me a while to decide which ones, though, since many are still fairly unknown.

I find the research process also very stimulating. For example, there are currently no official decompression schedules for ascents starting at 200 meters. I was my own guinea pig for that dive. I’d like to use statistics to see if the schedule I came up with can be improved, and if I could one day dive for longer and go further.