Taking a dip, part of efforts to ensure the river is safe for athletes, highlights the city's commitment to cleaning the iconic waterway, which will host swimming events during the Games, which get underway from 26 July until 11 August.

The 65-year-old, donning her goggle and wetsuit, gracefully swam breaststroke under the bright summer sun. She then immersed her face in the Seine and switched to a front crawl, covering approximately 100 metres downstream.

"It's wonderful, very, very pleasant," Hidalgo told reporters. "It's fresh but not cold." Joining her were senior local officials and Tony Estanguet, the chief organiser of the Paris Games and a gold medal-winning canoeist.

Estanguet has been diligently overseeing the Seine's cleanliness in preparation for the Paris Games, set to begin next week. "Today is a confirmation that we are exactly where we meant to be," Estanguet said. "We are now ready to organise the Games in the Seine."

Mayor of Paris, Anne Hidalgo, swam in the Seine Wednesday morning, in a bid to showcase of how clean the river is for the outdoor swimming events at the 2024 Paris Olympics, which open in just nine days.

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The Olympic triathlon's swimming segment will take place in the Seine on July 30-31 and 5 August, with open-water swimming following on 8-9 August. Despite a €1.4 billion ($1.5 bn) investment to stop sewage leaks, the river had consistently failed water quality tests until earlier this month.

Wednesday's swim, witnessed by over 150 journalists, aimed to prove the river's readiness and highlight one of Paris 2024's key legacy goals. Mayor Hidalgo plans to open three public bathing areas in the Seine next year, a century after swimming was banned. Additionally, the waterway is seeing a resurgence of fish and other wildlife.

Hidalgo had originally planned to swim last month but postponed due to water tests revealing E.Coli bacteria levels up to 10 times higher than permitted limits. Her swim sparked jokes and memes on social media, including a viral AI-generated image depicting her as the wrinkled Gollum from Lord of the Rings. Additionally, a brief protest movement with the hashtag #jechiedanslaSeine (#IshitintheSeine) urged people to defecate in the river upstream to protest against the socialist mayor.

President Emmanuel Macron, who had promised to join the Seine swimmers, was notably absent on Wednesday due to a political crisis following his decision to call snap parliamentary elections last month. Outdoor swimming locations for the Olympics have historically posed challenges, notably before Rio 2016 and Tokyo 2020.

"It's been raining all over France. Summer has been very late to arrive and so have the good results," said Marc Valmassoni from clean-water campaign group Surfrider. "They're not excellent, they're not terrible, they're average. But at this time the water is swimmable."

French authorities have invested in new water treatment and storage facilities around Paris and ensured that thousands of homes and canal boats without wastewater connections are now linked to the sewerage system. "If it hadn't been for the Games and Tony Estanguet, we wouldn't have been able to do all this work, because the Games were an accelerator," Hidalgo explained. However, major storms can still overwhelm Paris's wastewater network, causing emergency discharges of untreated sewage into the Seine.

Olympic events are weather-dependent, with heavy rains on the eve of the triathlon or open-water swimming potentially leading to issues. In a worst-case scenario, the triathlon swimming could be canceled, and open-water swimming might be relocated to a course east of Paris. 

Heavy rains in May and June have also affected preparations for the Seine-based opening ceremony, during which thousands of athletes are set to sail down the river. Organisers have had to postpone rehearsals multiple times due to strong currents, with the Seine's flow currently at 400 m³/second, significantly above the usual 100-150 m³/second for this time of year.