Protesters delayed a procession of cruise ships for over an hour on Saturday by leaping into Venice’s Giudecca canal.

The Telegraph reports that around 50 protesters dressed in wetsuits, backed by 1,000 supporters, delayed the ships by paddling in the canal. They believe the cruise ships are threatening the city’s foundations and want the port moved to an island away from the city.

The demonstration was timed to coincide with a busy day on the canal, with 12 ships due to head past St Mark’s Square, instead of the daily average of two.

Silvio Testa, a spokesman for the protesters, said: “The demonstration was a great success and we now hope the government will take advantage of this momentum and kick the cruise ships out of the Venice lagoon.”

Cruise ship operators claim the ships do little damage to Venice’s fragile palazzi.

Those in favour of the cruise ships say 5,000 local families are supported by the jobs guaranteed by the traffic, but protesters say the city’s character is being crushed by the amount of tourists arriving daily for short visits.

The mayor of Venice, Giorgio Orsoni, said: “The time for decisions has arrived, the big ships must go as soon as possible.”

Nine of the 12 ships which arrived in the city on Saturday were above 40,000 tonnes, the maximum limit set on ships passing through Venice by a government decree passed last year.

The decree, however, allows the ban to come into effect only when alternative routes have been found.

Andrea Orlando, the environment minister, said he would propose next month the gradual switching of ships to Marghera, a mainland port in the lagoon.