A Swedish ship with rights activists from several countries aboard sailed from Naples on Saturday in the latest bid to break Israel's blockade against Gaza.
A crowd of well-wishers saw off the sailing vessel Estelle as it left the Italian port as part of the "Freedom Flotilla" movement.
"We think it will take around two weeks to get to Gaza, but it will obviously also depend on the weather conditions," spokeswoman Ann Ighe said earlier.
The Estelle, whose voyage was organised by an international pro-Palestinian coalition, is carrying humanitarian goods to the Gaza Strip.
The 17 activists from around the world on board include passengers and crew from Canada, Israel, Norway, Sweden and the United States.
Israel says the blockade is necessary to prevent weapons from entering the coastal territory, which is run by the Islamist movement Hamas.
The first Freedom Flotilla in May 2010 ended in tragedy when nine Turkish nationals were killed after Israeli commandos boarded the Turkish-flagged Mavi Marmara, the lead ship, as it tried to break through the blockade.
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"When people think of flotillas, they think of the Mavi Marmara. But the Estelle is very different, she was chosen to change the perception of the campaign, to show that it's a non-violent campaign," Ighe said.
At just 53 metres (173 feet) long, the Estelle is much smaller than the Marmara ferry, and has sails as well as an engine.
"It is a vessel that has travelled for Greenpeace protests and on fair-trade missions. The Estelle is a peaceful ship," Ighe said.
Naples mayor Luigi de Magistris said Friday on visiting the Estelle: "This is not an initiative in favour of Hamas but in favour of Palestine, of the Palestinians who live in Gaza, and in favour of two states living as neighbours in peace and security."
The Estelle set off originally from Sweden and arrived in the Gulf of Naples on Thursday after a tour of Europe, including Finland, France and Spain. Its exact location can be followed on the flotilla's Ship to Gaza website (http://shiptogaza.se).
A second attempt to break the blockade last summer with a coalition of ships setting sail from Athens failed after Greek authorities intercepted the boats, banning their departure and towing back into port those who tried to leave.
In November last year, the Israeli navy also intercepted two Irish and Canadian ships carrying 27 passengers and crew that were trying to breach the blockade in international waters off Gaza.