Long ago the Venetian government decreed that passenger gondolas were to remain black.
The only white gondolas I know of in Venice are racing gondolas. Each official regata is rowed in a group of identical boats. The only differences being the rowers choices of forcole, remi, and the colors that the boats are painted. Typically there are nine colors and white is one of those colors.
You can see a few racing gondolas among the many Commune boats in front of Santa Maria della Salute church. I shot this photo from the vaporetto the day before the 2005 Regata Storica. Somewhere in there you can see a white one. The unusual "vents" in the tail are unique to racing gondolas.
There are rowing clubs in the Veneto who's color schemes may involve white, such as the Cannotieri Treporti, but again, not a passenger vessel taking riders for hire.
I am not above correction though, so if anyone out there has seen a white gondola taking passengers in Venice, Italy, I would love to hear about it.
I'd be surprised though, as that would be a big, highly visible violation of Venetian law.
The Venetian Casino in Las Vegas does have one white gondola in their fleet.
She is known as the "Wedding Gondola", and while she has the same hull and passenger layout as the other boats there, her deck-accents and other metal accessories are gold plated.
Here in Newport Beach, there are a number of white gondolas afloat. Joe Munday's "Crystal Swan" is white, just like many of the other gondolas he built over the last two and a half decades.
Joe Munday on his Crystal Swan
Gondola Romance also has three white gondolas which were all built in the early 80's.
Interestingly, all of America's white gondolas have been motorized except one - the mysterious white gondola of Venice, California. The only photograph of this boat was on a post card circulated in the very early 1900's. To read more on this vessel, see my post from March 4th of 2002
Venice, California in the first decade of the 20th Century.
Here in the US, white boat paint is much easier to come by. Compared to black, it is easier to keep clean too. But a white gondola, in a field of white boats, is another white boat - it tends to blend in. While a black gondola with a background of white boats stands out beautifully, leaving little doubt as to what type of vessel she is.
The story of a "very large white gondola" transporting couples from Isola di San Giorgio Maggiore is a new one to me. The presence of a white passenger gondola in Venice would be highly unlikely though.
I have seen a photo of another white, crescent-shaped rowing boat in Venice that did take passengers...of a different kind. Back in the days when the only motorized vessels in the city were the original vaporetto boats, everything else was rowed...including ambulances. In one photo of the Grand Canal, which I have but don't know if I can post, there are vessels that look like white traghetti, with felze-like tops, that have red crosses on sides.
Were they "ambulance gondolas"?
The photos I've seen of these vessels have all been monochrome, so I'm only assuming that they were truly white. They could just as easily have been light gray or even bright yellow.
I did see a white Venetian gondola with passengers once.
It was in a photo from Ingo Stahl in Germany:
But I understand that the white on that boat was temporary.