Cries of “It is warm!” rang out across the Seine on Saturday morning as Parisians jumped into the river — legally — for the first time in more than 100 years.

Public swimming was allowed in designated areas of the Seine, including two newly built wooden decks near the Eiffel Tower and the Île Saint-Louis in central Paris.

Before sunrise, a municipal officer skimmed away the last few patches of algae with a fishnet.

Soon after, a line of eager Parisians formed, towels in hand, waiting for their chance to jump in.

Woos and cries of joy echoed across the riverbanks as the first swimmers entered the emerald-green water.

Every swimmer wore a bright yellow lifebuoy tied around their waist, part of strict safety measures enforced by a dozen lifeguards in high-visibility vests.

The current was weak, just enough to tug gently at their limbs — a reminder that this is still a living, urban river.

“It’s so nice to swim in the heart of the city, especially with the high temperatures we’ve been having lately,” said Amine Hocini, a 25-year-old construction worker from Paris. “I’m surprised because I thought it was going to be cooler and in fact, it’s much warmer than I thought.”

The return to swimming follows a $1.5 billion cleanup project tied to last year’s Olympics.

Officials now say the Seine meets European water quality standards on most days.

Mayor Anne Hidalgo, who already took a dip last year, was there Saturday morning, holding up a transparent bottle filled with river water as a show of confidence.

Environmental authorities confirmed bacteria levels were well below official thresholds.

Swimming in the Seine had been illegal since 1923, with a few exceptions, due to pollution and risks posed by river navigation.

Taking a dip outside bathing areas is still banned for safety reasons.

From the deck, tourists and morning joggers stopped to watch.

Some applauded as swimmers climbed up the steel ladders, grinning and dripping.

Others, like François Fournier, remained skeptical.

“I won’t risk it quite frankly,” said Fournier, who lives atop the riverbanks and observed the scene from a bridge above. “I’ve seen things you can’t imagine floating in the Seine, so I’ll wait for it to be really squeaky clean.”

Floating debris still bobbed here and there — a stray leaf, a plastic wrapper — but the smell was barely noticeable: no strong sewage odor, just an earthy, river-like scent.

“This is so chic, to swim in the Seine, next to Île Saint-Louis,” said Lucile Woodward, 43, a resident.

“There are some apprehensions, of course, any time you go to swim somewhere, but I think this is one of the most tested areas in the whole world now. I don’t think the town hall can allow herself to have any problems.”

She added with a laugh: “My skin is OK.”