Just in time for the 2024 Summer Olympics, the river Seine in Paris will be clean enough to swim in for the first time in 100 years. This will allow the Olympics to stage events in one of the world’s most famous and photogenic rivers. A swimmable Seine will be a major turnaround for this busy urban waterway, which for many years has been notorious for its pollution. In 1923 the city banned swimming in the river due to high levels of waterborne bacteria and other dangerous pathogens. The clean-up is almost finished, and the water quality is already safe for swimming. The plans are to have public swimming in the Seine after the Olympics. In 2025 the city will open five permanent bathing facilities along the river. That network will be expanded across Greater Paris, creating up to 23 more swimming spots in the Seine and its upstream tributary the Marne.