The world's biggest iceberg — a wall of ice the size of Rhode Island — is lumbering toward a remote island off Antarctica that's home to millions of penguins and seals. The trillion-ton slab of ice — called a megaberg — could slam into South Georgia Island and get stuck or be guided around it by currents.

An iceberg about 1,500 square miles in size is on a collision course with a remote island in the South Atlantic. The world's largest iceberg, known as A23a, broke loose from Antarctica's Filcher Ice Shelf in 1986,