Thousands of people marched in Venice to demand that cruise ships be kept out of the Italian city's lagoon. The protest Saturday was galvanized by a crash six days earlier involving a cruise ship that struck a much smaller river boat in Venice's Giudecca Canal. The demonstration was organized by a group called "No Big Ships" following the incident in which the 13-deck MSC Opera suffered an engine failure, scraped along the dockside and knocked into a luxury tourist boat. Four tourists were slightly injured in the accident at San Basilio-Zattere.

Amateur footage of the incident was posted on social media, sparking a fresh controversy over the damage the mammoth vessels cause to one of the world's most famous cities, which along with its lagoon, canals, bell towers and bridges is a UNESCO World Heritage site.

Some marchers carried banners that read "Ships out of the lagoon." Others took to the Venetian Lagoon itself in rowboats and other small vessels to push a yearslong campaign to end cruise ship port calls. Critics say the waves the ships create are eroding the foundations of the lagoon city, which regularly floods, leaving iconic sites such as Saint Mark's Square underwater. Environmentalists have complained huge cruise liners wear down the city's fragile foundations in the Adriatic Sea and dredge up the lagoon's muddy bottom. Venice's mayor wants cruise ships rerouted from the heart of the lagoon. The ships disembark thousands of day-trippers.