Two boats carrying members of a US based pro-Palestinian group which is challenging an Israeli blockade on the Gaza Strip reached the shore of the Hamas controlled territory on Saturday.
The 44 "Free Gaza" activists from 17 nations, who had set out on Friday from Cyprus in two wooden boats, were met by hundreds of Palestinians who cheered along the shoreline at their arrival.
Israel initially said they would intercept the boats, but then allowed them in.
Israeli Foreign Ministry spokesman Arye Mekel said Israel's navy, which patrols the Gaza coastline, allowed the boats to enter Gaza "in order to avoid a well publicised provocation in the middle of the sea".
Israel imposed a blockade on Gaza in June 2007 when the militant group Hamas took control of the territory by force.
Since then, Israel has allowed in little more than basic humanitarian aid as a means of isolating Hamas and persuading militant groups to stop firing rockets into Israel.
The closure of Gaza's borders by the Israeli and Egyptian authorities has also meant that very few Gazans have been able to leave.
The boats were an attempt to bring attention to the sanctions Israel's imposed on the Gaza Strip, to isolate Hamas and stop militancy there.