For Parisians, the event holds an additional dream: the hope that, post-Games, the Seine, which has placed a taxi landing pad, will be transformed into a swimmable river, fulfilling a long-cherished aspiration for the city's residents to dive into its rejuvenated waters.

During the Olympics, the River Seine will host the swimming and triathlon events, marking a historic moment for the Games and the city of Paris. Athletes from around the world will compete in the Seine's waters, showcasing their endurance and skill against the backdrop of Paris's iconic landmarks. 

This ambitious use of the river aims to highlight its revitalisation efforts, turning it into a vibrant venue for Olympic competitions and underscoring the city's commitment to environmental restoration. As part of the Paris 2024 Olympics festivities, an urban beach will be set up near the Eiffel Tower, transforming the heart of the city into a sun-soaked retreat. 

This temporary beach oasis will offer both locals and visitors a unique riverside experience with sandy shores, lounge chairs, and recreational activities right by the Seine. Nestled beneath the iconic Eiffel Tower, the urban beach will feature beach volleyball courts, paddleboarding, and a relaxing space to enjoy the picturesque views of the Seine and the Parisian skyline.

Once seen as an open-air dump, the idea of swimming in the Seine was first proposed by former French President Jacques Chirac in 1990. However, it was the current mayor, Anne Hidalgo, who truly championed the concept, making it a central element of her Olympic bid in 2016.

Around €1.4 billion have been invested in massive public works to combat pollution, with Hidalgo pledging to swim in the Seine next week to demonstrate its cleanliness.

The water quality of the Seine fluctuates significantly after major rainstorms, which cause untreated sewage releases and cast uncertainty on whether Olympic swimming events can proceed. Last August, disastrous test events highlighted these concerns when the water failed to meet European standards due to high bacteria levels, exacerbated by severe storms and a faulty sewage valve.

This led to reigning Olympic marathon swimming champion Ana Marcela Cunha calling for a "plan B" to ensure athlete safety. Recent pollution tests continue to show problems, though the upcoming dry weather may improve conditions. 

While only a few people swim in the river, their experiences have been mixed; lifeguard Gaelle Deletang suffered health issues from swimming, and young adventurer Arthur Germain encountered pollution and high faecal matter levels throughout his 2021 journey along the Seine, especially near Paris.

Despite past pollution issues, the quality of the Seine's water has been steadily improving due to significant anti-pollution efforts. Five major treatment plants have been launched, wildlife is returning, and the amount of garbage in the river has decreased from 325 tonnes to 190 tonnes in 2020. 

Remi Delorme, who has been fishing rubbish from the river since 1980, notes a clear reduction in waste. A 2018 law now ensures that boats are connected to the city's sewers, and efforts to fix leaking sewage pipes from 23,000 suburban homes have cut wastewater discharges from 20 million to 2 million cubic meters per year.

Hydrologist Jean-Marie Mouchel has seen notable improvements in the Seine’s health, with better oxygenation and reduced pollutants leading to over 30 fish species returning since 1970. Fisherman Bill Francois has recently caught a large catfish and a perch, evidence of the river's recovery. 

Microbiologist Francoise Lucas believes that while all technical measures have been taken, the weather will ultimately determine the success of the Olympic events on the Seine. Upstream from Paris, a modernised sewage plant is now using performic acid, an "organic disinfectant," to treat wastewater safely and effectively.

Nearby, a new stormwater control station at Champigny-sur-Marne filters and cleans rainwater to prevent pollution, while a massive stormwater cistern near Austerlitz station, capable of holding 20 Olympic swimming pools worth of water, acts as a backup to prevent sewage overflow into the Seine. Despite these measures, Prefect Marc Guillaume acknowledges that occasional rainstorms may still exceed the system’s capacity.