Large cruise ships are to be banned from entering Venice's historic centre, the Italian government says.
Ships weighing more than 1,000 tonnes will be rerouted away from certain waterways from September.
The move follows an accident in June in which a ship collided with a dock, injuring five people.
But conservationists say the government's plans are insufficient to prevent underwater erosion and pollution in the lagoon city.
Starting from next month, some liners will be forced to dock at the Fusina and Lombardia terminals away from the city centre, the Financial Times reported. By the end of 2020, a third of all ships will be rerouted.
Critics have long said waves created by cruise ships on the canal erode the foundations of the city, which regularly suffers from flooding. Others have also complained that they detract from the beauty of Venice's historic sites and bring in too many tourists.
But the June accident, in which the MSC Opera - a 275m (900ft) long ship - collided with a dock and a small tourist boat in the city's Giudecca canal, galvanised protesters to call for a definitive ban.
The Giudecca, which passes close to the popular St Mark's Square, is one of Venice's major waterways.
In 2013, the government banned ships weighing more than 96,000 tonnes from the central Giudecca canal, but the legislation was later overturned.
In 2017, it was announced that larger ships would be diverted from the historic centre, but the plans were expected to take four years to come into force.