On Aug. 4, the Viking Sea, a 930-passenger cruise ship, docked in Italy’s Venetian Lagoon. At first sight, the scene looked familiar: a towering white vessel, loaded with tourists, most of them from North America, making its way past centuries-old buildings and narrow canals. But this time the destination wasn’t Venice, but Chioggia, a smaller, lesser-known city built on a separate cluster of islands about 15 miles away, in the same lagoon.

Following a series of protests from environmental groups last year, the Italian government recently started enforcing a ban on large cruise ships weighing more than 40,000 tons from the San Marco basin, the portion of the lagoon surrounding Venice’s historic center.