A68a the world’s biggest iceberg heads for disaster Manhattan Island, World’s biggest iceberg heads for disaster The mass is now moving straight toward a remote south Atlantic island populated by penguins and seals. Scientists say a collision could cause a local, environmental catastrophe. By Iceberg A68a has been on a slow journey toward cataclysm. The mass broke from the Antarctic peninsula’s Larsen C ice shelf in July 2017 and headed slowly for the open ocean, sliding through the water for over two years until it hit the powerful Antarctic Circumpolar Current circling the southernmost continent. And then, like a speed skater, it was on its way. The current propelled the berg on a fast track through what scientists call “iceberg alley,” a northeast route traveled by chunks of ice that break from the peninsula.