The mishap happened after the gondolier warned the group of Chinese visitors not to shift over to one side of the boat as he negotiated a bridge.
They ignored the advice – and ended up in the freezing water.
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“Even though the gondolier shouted at them not to do it and to desist because it was dangerous, they continued. Almost all the weight on one side unbalanced the boat, which capsized,” local paper La Nuova reported.
The gondolier helped get the tourists out of the water and emergency services were called, the paper said.
Footage show the tourists with their hair wet clinging to the side of the boat.
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It happened in Rio de la Verona near St Mark’s Square.
Instagram page Venice is not Disneyland said they were taken into a tailor’s shop to dry off.
Most of the smaller canals are only 1.5 to 2 metres deep.
The gondolas date back to 11th century when they were used by Venetians to get between the over 100 islands.
Now tourists can take a half hour ride from $130.