The sites, including Grenelle with its view of the Eiffel Tower, are part of a €1.4bn clean-up project that has made the river suitable for Olympic events.
Each location is monitored by lifeguards, with water quality tested daily to meet EU standards.
Officials say visitor numbers could rise sharply as a heatwave brings temperatures of up to 38°C, triggering a “high vigilance” alert from Meteo France.
More than 40,000 swimmers have visited so far, despite several closures caused by heavy rainfall.
