A group of Canadians boarded flights Sunday to join a ship convoy that is going to try to bring aid to Palestinians in the Gaza Strip.
The group was planning to meet in Greece on Monday and join an international flotilla that is expected to set sail in the coming days.
Israel has indicated it will stop the ships from getting to Gaza, which is under an Israeli naval blockade.
Lyn Adamson, one of the 32 Canadians taking part, called on the federal government to support the mission and take a stance against the blockade.
A flotilla to Gaza last year ended in bloodshed, when nine activists were killed and 45 injured after Israeli soldiers boarded a Turkish ship.
Adamson is concerned for the group's safety but said passing on the trip would be "unconscionable."
"It's simply a humanitarian mission and we want to help the people in Gaza get back on their feet," she said Sunday before boarding a flight in Toronto.
"The Israelis don't seem to understand that, and they have threatened many things.…Our government should be standing up to them."
Foreign Affairs Minister John Baird has called the convoy "provocative."
Manon Massé, another Canadian delegate leaving Sunday, said such comments are an attempt by Prime Minister Stephen Harper's government to turn attention away from the humanitarian goal of the mission.
"Of course we want to provoke, but not the Israeli army," said Massé, a candidate for the provincial Québec Solidaire Party. "We want to provoke the international community and civil society to say to Israel: 'Stop.'"
The Canadians say they are bringing medicine and medical supplies to the Palestinians, and are open to having the boats inspected by the United Nations or another third-party group.
Israel, however, has vowed to prevent the flotilla from docking.
On Sunday, an Israel navy commander extended a stern warning to organizers.
"The navy has prevented and will continue to prevent the arrival of the 'hate flotilla' whose only goals are to clash with [Israel Defence Forces] soldiers, create media provocation and to delegitimize the state of Israel," Admiral Eliezer Marom said during a graduation ceremony of members of Israel's navy, according to the Israeli newspaper Ha'aretz.
The Canadians are to be joined on the 10-ship convoy by delegates from Australia, Belgium, Denmark and Germany.