The activists, including European lawmakers, were sailing on a flotilla attempting to break Israel's blockade of Gaza when their vessels were intercepted, drawing widespread condemnation and sparking protests around the world.
The Global Sumud Flotilla was the largest yet to try to break the blockade, and it comes at a time of growing criticism of Israel's conduct in Gaza, where its offensive has laid waste to swathes of territory and killed tens of thousands of people.
Activists had said they hoped that the sheer number of boats would make it more difficult for Israeli authorities to intercept them all, but Israel's Foreign Ministry declared the operation over on Thursday afternoon.
Israeli police shared a video showing some 600 officers working on the Jewish holiday of Yom Kippur, considered the holiest in the Jewish calendar, to register the detained activists ahead of their expected deportations.
Thousands of people supporting the flotilla took to the streets in several major cities after news of the interception broke to decry the Israeli operation and the ongoing offensive in the Gaza Strip. Italy's largest union called for a one-day general strike on Friday.
While the majority of marches were peaceful, clashes erupted between police and pro-Palestinian protesters in Paris and in Barcelona, Spain.
The flotilla, which started out with more than 40 boats and some 450 activists, was carrying a symbolic amount of humanitarian aid to Gaza. Its main goal, they said, remained "to break Israel's illegal siege and end the ongoing genocide against the Palestinian people".
Israel's Foreign Ministry dismissed it as a "provocation", saying various countries have offered to deliver the aid the boats were carrying. Israel has come under intense criticism for how much aid it lets into Gaza and how it distributes the goods. It has vehemently denied it is committing genocide.
The Hamas-led attack on southern Israel on October 7, 2023, triggered this war. Militants killed some 1200 people that day, while 251 others were abducted. Forty-eight hostages are still held in Gaza, with around 20 believed to be alive.
Israel's ensuing campaign has killed more than 66,000 Palestinians, according to Gaza's Health Ministry, which does not differentiate between civilians and militants in its toll.
Israel has maintained varying degrees of blockade on Gaza since Hamas seized power in 2007, saying it is necessary to contain the militant group. Critics deride the policy as collective punishment.
After the war started, Israel tightened the blockade but eased up later under US pressure. In March, it sealed the territory off from all food, medicine and other goods for two-and-a-half months, contributing to Gaza's slide into famine.
The flotilla said it wanted to establish a humanitarian corridor by sea, given the little aid that was reaching Gaza by land.
Israeli forces detained and removed dozens of people from the flotilla including Greta Thunberg, former Barcelona Mayor Ada Colau and European Parliament member Rima Hassan.
Turkey, Colombia, Pakistan and others condemned Israel's interception of the flotilla.
Italy, France, Poland and other European nations, which had warned the activists not to continue the journey and avoid confrontation with Israel, said they were working with Israeli diplomatic authorities to ensure their citizens were transferred to land and deported home swiftly.
Israel has argued its actions constitute a lawful naval blockade needed to prevent Hamas from importing arms, while critics consider it collective punishment of Palestinians in Gaza.
