I'm not even sure when this photo was taken.
Obviously it was after the advent of photography (duh!).
There are a number of things in the picture that could hint towards a date, but it's hard to say.
The flags all have the crest in the center of the white field, and while that hasn't been the official flag of Italy since 1947, you can still see them flying in Venice today.
The costumes on the gondoliers and some of the other people in the photo look like they could be from the 30's or 40's.
The gondolier farthest to the right has a unique collar, unlike any of the others. It looks like it might actually be part of a naval uniform.
What I find curious is the "rafting" - there are seven gondolas side-tied to each other.
It reminds me of how everyone rafts up to watch regatas today.