Crew members of a French nuclear submarine who were logging runs on the fitness app Strava have risked leaking their position and patrol schedule to Russia.
Strava allows members to share their sporting activities online and includes a map showing the location where the user completed the exercise.
Île Longue in Brest Harbour in Finistère is home to four nuclear submarines, each capable of carrying 16 nuclear missiles about a thousand times the power of the Hiroshima bomb.
Patrols by land and sea by drones are carried out around the clock to ensure security and more than 2,000 employees must show identification to enter.
Mobile phones are prohibited and must be stored in lockers at different checkpoints on the base.
Despite the strict security surrounding the facility, sensitive information was still able to leave the fortress due to users of the fitness app.
In the past 10 years, more than 450 Strava users have been active within the walls of the compound.
Many of those users have not used pseudonyms and have kept their profile public, which allowed journalists from Le Monde to discover the identities of people on the base.
Runs logged by crew members on a French naval base were posted online on the fitness app Strava (stock)
A nuclear submarine leaving Brest Harbour, where l’ÃŽle Longue naval base is located (pictured in 2007)
Submarine crew tracking their runs have risked times of patrol schedules being leaked to foreign powers (stock)
One example was Paul, not his real name, who in January 2023 recorded 16 activities.
On February 3, 2023, he ran along the docks where the submarines are moored, recording his times and locations on the app.
Then for the next month his account went quiet and he suddenly stopped using Strava.
He was not active again until March 25, 2023.
Similarly, Strava users Arthur and Charles, not their real names, also abruptly stopped their training on Strava after February 3 and resumed around March 25.
This suggested that all three men began a patrol aboard one of the submarines.
To confirm this, Paul also justified his disappearance from the app, saying: ‘It’s tough to get back into sport after more than two and a half months in a poo box.’
He posted the message attached with emojis representing bubbles and a diving mask.
A map of the Ile Longue naval base near Brest on the west coast of France
The nuclear attack submarine Emeraude is pictured at Brest’s naval base, western France
The French Navy told Le Monde that despite the mobile phone ban, smart watches could have passed security, allowing the men to record their runs on the base.
The Navy acknowledged that there was ‘negligence on the part of the personnel which do not necessarily constitute flaws that could affect the activities of the operational base on ÃŽle Longue’.
Strava activities could have allowed a foreign power to anticipate a nuclear submarine’s departure.
The last races completed by Paul, Arthur and Charles before their departure were on the docks where the submarines are moored, an area where access is strictly controlls and sports activities are rarer than on the athletics track.
Runs taking place on the docks could therefore signify the imminent departure of one of the submarines.
