The almost 20 months of war has torn Gaza apart, often displacing residents multiple times and killing more than 54,000 people, according to the Hamas-run Health Ministry. A U.S.-brokered ceasefire agreed in January collapsed in March as Israel enforced a blockade on all humanitarian aid into the strip.

Thunberg and 11 other activists are on board a ship headed to Gaza with aid supplies, but the IDF has said it does not intend to allow the ship to dock.

A vessel organized by an international activist coalition to deliver humanitarian aid to Gaza has rescued several migrants from the sea near Crete.