But the ship never arrived.
It was turned back by the Israeli navy, ending the first high-profile attempt to break the blockade of Gaza. Analysts said the incident showed that Arab and Muslim nations, while eager to end Gaza's isolation, won't risk military confrontation with Israel over it.
Israel views control of access to Gaza as a vital security interest, concerned that shipments could include weapons, not just food and medicine.
Israel imposed a blockade on Gaza after the violently anti-Israel Hamas seized power last year, tightening the closure in recent weeks when Gaza militants resumed firing rockets at Israel.
"The Arab world is not very happy about the siege Israel has imposed on Gaza, and they are trying to break it," said analyst Moshe Maoz of the Hebrew University of Jerusalem. "They can only blame and denounce Israel, but they won't fight."
Gaza's borders have been largely sealed by Israel and Egypt since the Islamic militant Hamas took control by force in June 2007. Occasional passage as been allowed for medical patients, Muslim pilgrims, humanitarian supplies and a trickle of commercial goods.
Israel's closure has led to shortages of cooking gas and other essentials as well as frequent power outages.
The Libyan attempt to reach Gaza came amid increasing discussion in Arab and Muslim countries about providing aid to Gaza in spite of the blockade.
Last week, Arab foreign ministers said in a joint statement in Cairo that their governments would send food and medicine to Gaza, though they did not specify how.
Since Egypt has also retained tight control over its border with Gaza, outsiders are increasingly considering the one remaining way into the territory: the sea.
Since this summer, international activists have organized three trips from Cyprus to Gaza on smaller boats. Israel did not stop these, allowing the vessels to deliver some medicine and other supplies.
Other groups seek to follow their lead.
The non-governmental Qatar Charity on Monday announced plans to send one ton of medical supplies to Gaza by boat later this week. The group expects the Israeli navy to stop the ship, said director Abdallah Naema.
Turkish lawmaker Suleyman Gunduz is working with Turkish NGOs to send a boat to Gaza carrying aid, doctors and intellectuals. "It is going to be a symbolic voyage to show that we must take medical and humanitarian aid to the region," Gunduz said.
The fate of the Libyan ship does not bode well for future efforts.
Israeli Defense Ministry spokesman Shlomo Dror said Hamas must stop rocket fire if it wants free movement of goods in and out of Gaza.
He said the Libyan vessel was stopped for security reasons. "This (Libya) is a country that, as much as we know, is supporting some kinds of terror acts, and if the Palestinians really need humanitarian supplies, there is a way to bring in these supplies though the crossings," he said.
Mouin Rabbani, a Jordan-based Middle East analyst, said the previous boats were largely symbolic and had done little to upset Egyptian and Israeli control of access to Gaza.
"But once you have real ships filled with goods coming in, you're not just breaking the siege. You're beginning to set a precedent because you have an alternative source of supplies that don't rely on either Israel or Egypt," Rabbani said.
Despite the failed effort, Hamas spokesman Fawzi Barhoum praised Libya and called on Egypt to open its border to allow Arab and international assistance to enter Gaza.
Also Monday, Israeli reporter Amira Hass returned to Israel from Gaza after Hamas officials told her to leave because of security concerns.
Hass, an award-winning reporter for the Israeli daily Haaretz, arrived in Gaza by boat last month. She defied her country's ban on Israeli citizens entering Gaza.