It is one of the few statues in Italy dedicated to women and, according to the tourist, a perfect spot for a travel picture.
The picture was likely not worth the €463 (NZ$780) penalty and 48-hour ban from the city.
Mario Nason, a Venice local, told CNN he was walking with his son when they spotted the women and two companions on the waterfront monument.
"It was a beautiful day and we saw two people taking photos. I saw a strange movement and then I saw this woman swimming without a care in the world," Nason said.
"I thought she must be crazy, thinking she could swim on a freezing day.
"But then I saw she was trying to get out of the water by climbing onto the statue, wearing just her bikini bottoms.
"She got up on it, then she got back into the water, totally relaxed.
"Her boyfriend and another woman had jumped over the barrier and were on the monument, to take better photos of her. They were stood there beside her clothes that she'd left [on the monument], just as you do on the beach."
After being apprehended by police, the woman (who remained unnamed) was given a
€350 (NZ$590) fine, antisocial behaviour order and a 48-hour ban which includes an additional €100 (NZ$170) fine.
"It was incredible because [the tourists] were asking, 'How is this a problem?' They didn't have the slightest inkling of what they were doing," Nason told CNN.
"It's like going to Rome, leaping in the Trevi Fountain and then saying, 'What do you mean, you can't do this?'
"You can say, whatever, they haven't killed anyone. But when I travel, if I see a fountain, I don't have the urge to jump in. If I'm in Paris, walking along the Seine, I don't throw myself into the river. If I went to Prague, threw my clothes on a monument and went for a swim, would nothing happen? It's common sense. Why do people do these things in Venice that they wouldn't do elsewhere?"
The women had been attempting to imitate the dead partisan for a photo according to reports from local police.
"She wanted the statue in the shot," a local police spokesperson told CNN. "I imagine she apologized."
This is just the latest in a long history of bad tourist behaviour in Venice. A week prior, a man swam naked in the Grand Canal but was never caught.
In 2019, a German couple was also kicked out of the city after being caught making coffee on a camping stove beneath the Rialto Bridge.
"Sitting in St. Mark's Square with a slice of pizza, or brewing coffee, is a marvellous thing to put on Facebook, but if 30 million tourists behave like that, Venice becomes a beach or a campsite," Nason said.
"This goes beyond the personal upset of the sensitivity around the partisan monument. They probably didn't know the statue of the woman lying there was a dead partisan. But it's treating Venice like a beach.
"Just because you have the urge to do something, doesn't mean you should do it."
