Stopping Venice choking on its own pollution
Less well-known is that Venice is also choking on its own pollution.
Hundreds of diesel-powered vaporetti - commuter boats or water buses - spew out tonnes of carbon as they zigzag through the city's canals. Zipping to and from the Italian mainland, they ferry the 25 million tourists that visit annually, as well as food, hotel laundry and goods.
But some in this climate-challenged city believe they have at least a partial answer to Venice's environmental problems; an alternative vaporetto powered not by diesel but by hydrogen, a fuel that emits only water vapour when burnt and none of the carbon or greenhouse gases which cause pollution and climate change.