Tip of the iceberg
Icebergs can be very big. But what we see above water is only about 10 per cent of their total size. This is the origin of the expression 'the tip of the iceberg' that describes a problem that is much bigger than it seems.
Icebergs are very dangerous to shipping. In April 1912, the passenger ship Titanic set sail from Britain to the United States on its maiden voyage. The huge ship, then the largest of its type in the world, was said to be unsinkable. On a calm but freezing night, an iceberg was sighted too late to avoid a collision. Two hours and 40 minutes later, the Titanic sank, claiming the lives of more than 1,500 of its 2,223 passengers and crew.
Interesting facts
Most people assume that all icebergs are white. Most are, but they come in other colours, too. Sometimes they can be blue. Other times they are even green when there is algae inside the ice. Blue icebergs have pockets of air inside them. Even though icebergs are found at sea, they are made of freshwater.
Anywhere from 10,000 to 15,000 icebergs form in the Arctic every year. Most last about four years. Nobody is sure how many form in the Antarctic - there are too many to count. Some old sailors say that you can hear an iceberg in the distance: they make popping sounds. Others claim they smell like cucumbers!