A boat carrying a group of Jewish activists has set sail from northern Cyprus with the aim of breaching Israel's blockade of the Gaza Strip.
The 10m (32-foot) catamaran is carrying supplies including medical equipment, textbooks, nets and children's toys.
The activists - from Israel, the US, Germany and the UK - say they will not resist if Israel tries to stop them.
Earlier this year, Israeli commandos killed nine people in clashes on board a Turkish ship trying to reach Gaza.
Israel says its naval blockade is designed to prevent weapons being smuggled to Hamas militants who run the territory.
The boat, named Irene, set sail on Sunday under a British flag with 10 passengers and crew. It could take up to 36 hours to reach the Gazan coast.
Richard Kuper, a member of the UK-based organising group Jews for Justice for Palestinians, said it was a symbolic act of protest and also a message of solidarity to "Palestinians and Israelis who seek peace and justice".
"This is a non-violent action," he said.
"We aim to reach Gaza, but our activists will not engage in any physical confrontation and will therefore not present the Israelis with any reason or excuse to use physical force or assault them."
Among the activists is 82-year-old Holocaust survivor Reuven Moskovitz.
"It is a sacred duty for me, as a [Holocaust] survivor, to protest against the persecution, the oppression and the imprisonment of so many people in Gaza, including more than 800,000 children," he said.
Another passenger is Rami Elhanan, 60, an Israeli whose daughter Smadar died in a suicide bombing at a shopping centre in Jerusalem in 1997.
He said reconciliation with the Palestinians was the surest path to peace.
"Those 1.5 million people in Gaza are victims exactly as I am," he said.
However, Israeli foreign ministry spokesman Andy David called the protest "a provocative joke that isn't funny".
"It is unfortunate that there are all kinds of organisations involved in provocations that contribute nothing and certainly don't contribute to any kind of agreement," he said.
"If they were serious about wanting to transfer aid to Gaza, they could easily do so after undergoing a screening for smuggled weaponry."