Eleven European politicians set sail to Gaza from Cyprus on Friday after saying attempts to get to the Palestinian territory via Egypt failed.
Members of parliament from Britain, Ireland, Switzerland and Italy left the Mediterranean island on a boat arranged by a pro-Palestinian group.
"We were going to witness the living conditions in Gaza. We were not allowed through the Rafah crossing so we are going by boat because it is the only way to get in," said British MP Clare Short.
The parliamentarians said they expected to arrive in Gaza early on Saturday. It is the third time the US-based Free Gaza Movement has sailed from Cyprus to Gaza since August.
Israel has repeatedly announced that it would prohibit the group's boats from arriving at their destination, but the two previous sails have been successful. Angela Godfrey-Goldstein of the Free Gaza Movement told Ynet that this was good news.
"We are very pleased, and I believe people in Gaza are pleased as well and hope that Gaza's sea border remains open from now on."
The sea-goers are taking a metric ton of medical supplies and three medical scanners used for spinal injuries, said Arafat Shoukri, 37, a doctor based in Britain.
"We are taking very basic medical supplies like paracetamol and painkillers. We were shocked when we got the list from the Health Ministry in Gaza, it means they don't have anything," Shoukri said.
Short, a former minister in Tony Blair's government, said: "We want to witness the living conditions of these people, challenge the siege, and challenge the failure of our governments to uphold the Geneva convention. The whole of the EU is colluding to what is taking place in Gaza to our shame."
Organizers of the boat shuttle said more activists would travel to Gaza in mid-December, and a boat of European musicians would travel there in January.