The River Seine flows through the heart of Paris. It winds past the Louvre Museum and streams underneath the Eiffel Tower.
It will play a central role in the French capital's city-center Games, hosting the long-distance swimming and the aquatic leg of the triathlon.
The set-piece opening ceremony on Friday will also take place on the Seine.
But public swimming has not been allowed for a century, and many trial events have been cancelled because of heavy rain and bacteria in the water.
A contaminated Seine when the Games begin is a huge concern. Regular tests on the river have shown that the level of bacteria, especially E.coli, in the Seine has been a persistent problem over the last few months leading into the Games.
The Eiffel Tower, as seen from the Seine. /Pawel Kopczynski/Reuters
Speaking to CGTN, the head of the organizing committee for the Olympics said there was no change to the plan for the events in the Seine.
"We are still confident with the delivery of the competition on the River Seine and the opening ceremony on the River Seine," said Tony Estanguet, the president of Paris 2024.
"We knew from the beginning that the plan that we decided was really aligned with the good conditions at the end of July and we knew that we never tested this to make it feasible during the winter or even spring."
A municipal employee demonstrates the sampling of the water of the River Seine near Notre-Dame. /Gonzalo Fuentes/Reuters
But some Parisians have taken matters - or in this case - magnets - into their own hands.
Teo spends his free time cleaning the canals in the north of the city. He removes discarded metal objects, from wires and batteries, to knives and even bullets from the water. He is one of a number of people who do this in Paris - and he thinks the city authorities missed out by not letting magnet-fishers to help with the cleaning operation.
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"I think that if we had done it two years ago, then the river quality would have been a bit better, though maybe not greatly," said Teo Lhomme Fauveau.
"It's not just about objects in the river, it's about bacteria and what we find isn't really connected to that issue, but I think that we could have improved things for the Olympics."
A triathlon test event was held in the Seine in August 2023. /Stephanie Lecocq/Reuters
The Paris authorities have spent more than $1 billion on plans to make the river swimmable.
A giant water tank has been built underground which will collect rain run-off and prevent wastewater from entering the Seine. The tank can hold the equivalent of 20 Olympic swimming pools of dirty water.
If Paris does succeed in cleaning up the Seine, the project may become a blueprint for cities across the world. The legacy ambition is that from next year, Parisians will be able to follow in the swim-strokes of Olympic champions - and bathe in the river once more.
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