I wouldn’t even touch the water in Venice, even if you could force me to go there.
Visit Venice if you get the chance. Give it at least three full days, maybe four. That’s just scratching the surface, of course and if you fall in love with the place you can always go back. but you will find that you can’t even begin to do the tourist 101 thing in two days.
But yeah, don’t swim in the canals.