Resolves Yes for each of these people on report of them swimming in the Seine in credible news outlet. For the purpose of this market, I will accept either top English speaking news outlet, or top French news outlet as credible. If pushed in the Seine involuntarily, counts as Yes if the person in question does at least 5 seconds of swimming before being saved by their security detail (captured on camera for verification).
This market will close on August 12th 2024, whereupon all people who have not Seine-swam will resolve No.
In case of (hopefully unlikely) ambiguity, I reserve the right to close trading, discuss in the comments, and even resolve N/A.
Both Hidalgo and Macron have tentatively promised they would do it, but of course promises only bind those that would believe in them.