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An iceberg is a huge piece of ice that floats in the sea. Some icebergs are many miles long. They are always bigger than they look. Most of the iceberg is underwater.

Image to left: The top of an iceberg melts, leaving the bottom underwater. The hidden ice is dangerous to ships. Credit: World Book diagrams by Marion Pahl

Icebergs in the North Atlantic Ocean come from Greenland. They break off the ice sheet that covers Greenland and fall into the sea. Icebergs also come from the Antarctic icecap. Some of these icebergs are many times larger than those found in the North Atlantic. When an iceberg starts to break away, it makes noises that can be heard for miles. It sounds like loud explosions and rolling thunder. When it drops into the sea, it causes huge waves.

Icebergs can be dangerous to ships. The famous ship Titanic struck an iceberg and sank in 1912. About 1,500 people died.

How to cite this article: To cite this article, World Book recommends the following format: "Iceberg." The World Book Student Discovery Encyclopedia. Chicago: World Book, Inc., 2005.