Blue icebergs are icebergs that appear blue because of the way that light is dispersed throughout them. Red light on the visible end of the light spectrum is mostly absorbed, leaving blue light to scatter. This unabsorbed blue light emits a blue hue from the iceberg.
Although they are found in the ocean, icebergs are comprised of fresh water. They form when large chunks of ice breakaway from glaciers. In the northern hemisphere, most of the icebergs have broken from glaciers formed in Greenland. In the southern hemisphere, Antarctica is the origin of most icebergs. Because the majority of icebergs are not visible above water, they pose a danger to ships.