Icebergs are huge chunks of ice floating in the sea.
These icebergs were pieces of glacier. Only the tip of an iceberg shows above water.
Tons of glacial ice remain underwater, making icebergs particularly hazardous to ships.
Remember the Titanic! On its first voyage, in 1912, the 46,000-ton (46,736-metricton) ocean liner—which was said to be unsinkable—hit an iceberg. It sank.