Paris Mayor Swims in Seine, Says It's Clean for Olympics After Poop Protest Threats

Paris' mayor hopped into the Seine and walked away clean ... a huge relief to her 'cause tons of people said they were going to relieve themselves in the river to protest.

Mayor Anne Hidalgo jumped into the world-famous river for a quick dip to show her fellow Parisians the Seine's clean enough to host open-air swim events and opening ceremonies for the Olympics.

Check out the pics ... Hidalgo's doing her best Katie Ledecky impression as she works her way across the choppy river water in her wetsuit -- followed closely by a couple other top Paris officials.

Hidalgo told the assembled media the water's nice and refreshing ... and, most importantly, totally clean for the Olympics which kick off next Friday -- good news since French protesters threatened to turn the river into their personal toilet last month.

ICYMI ... after Hidalgo and French President Emmanuel Macron -- who didn't attend the swim -- offered to swim in the river to prove it was safe enough for athletes, protesters said they planned a defecation demonstration -- saying they'd take dumps in the river to stick it to their politicians.

In fact, a website showed French people outside Paris when to poop in the river so their "gifts" would reach the politicians in time and the hashtag “jechiedanslaSeine” -- "I'm pooping in the Seine" -- trended on X. Hidalgo ended up delaying her swim because of recent snap elections in the country ... though we imagine the fecal fanatics didn't help.

BTW ... a monitoring group called Eau de Paris has been testing the water for months and recently claimed there was an unsafe amount of E.coli present -- hence the pol's plunge. NBC News reports these levels have improved since they were first reported in early June.