An all-women flotilla is sailing to Gaza aiming to break the Israeli blockade.
Some 20 activists of different nationalities set sail for the Gaza Strip from Barcelona on Wednesday.
"We think that through this act organised by women, we can give more visibility to the important role of Palestinian women in the fight for freedom," said Zohar Chamberlain, one of the organisers, just before two yachts left the Spanish city.
The flotilla that set sail from Barcelona, named "Women's Boat to Gaza", is part of the wider Freedom Flotilla Coalition that consists of pro-Palestinian crews that frequently sail to Gaza to try and break the decade-long blockade.
None have yet managed to get through, and Israeli authorities have made several arrests.
Israel says the blockade is necessary to prevent Hamas from receiving materials that could be used for military purposes.
But the World Bank and United Nations say it has put an end to virtually all exports from Gaza and undermined the economy of the small coastal enclave.
|Read also: UN: Palestinian economy could double without Israeli occupation|
The blockade also severely restricts the movement of the 1.9 million Palestinians living in Gaza.
Chamberlain, an Israeli living in Spain, said she felt she had "double duty" to denounce the land, sea and air blockade imposed in 2006 on Gaza, which is controlled by Islamist group Hamas.
It "doesn't only make Palestinians suffer, it corrupts the souls of Israelis as one can't remain human if one treats our Palestinian brothers as if they weren't our brothers", she said.
The women travelling on board the two boats, Amal (hope)and Zaytoun (Olive), come from countries such as the United States, Norway, South Africa or Malaysia.
They are due to stop in several ports on the way, including Ajaccio in France's Corsica, to take other activists on board and hope to arrive in Gaza in early October.
A similar operation turned to tragedy in 2010 when Israeli commandos killed 10 Turkish activists in a raid on a flotilla.