An iceberg more than four times the size of Manhattan has been slowly drifting along Canada's eastern seaboard, according to NASA.

Chunks of the giant iceberg - dubbed Petermann Ice Island - have broken off and rubbed up against some Canadian shores, though NASA said the iceberg was not likely to h it land, but probably run aground on the sea floor just off the coast, posing a real danger to offshore oil rigs and ships at sea.

The 97-square-mile piece of ice broke from Petermann Glacier in Greenland a year ago, according to NASA Earth Observatory.