How much of an iceberg is hidden underwater?
Quick Answer
About 90% of an iceberg is hidden underwater: ice is less dense than seawater, so it floats, but only about a tenth of an iceberg shows above the surface — the rest lies hidden below.
The Full Story
When water freezes, its molecules lock into an open crystal structure, making ice about 9% less dense than liquid water. Glacial ice has a density of roughly 0.92 grams per cubic centimetre, while seawater is about 1.025, so an iceberg floats with roughly 90% of its mass underwater. Icebergs are chunks of freshwater ice that break off, or calve, from glaciers and ice shelves, mostly around Antarctica and Greenland. Because so much of their bulk is hidden, their underwater parts can extend far beyond what is visible, making them a danger to ships. After the Titanic sank in 1912 following a collision with an iceberg, the International Ice Patrol was set up in 1914 to track icebergs in the North Atlantic.
Key Facts
YouTube Angle
Suggested video title for this topic:
"The tip of the iceberg — why 90% of it hides beneath the waves."