Iceberg Blue

(click to enlarge)

(click to enlarge)

Many Antarctic icebergs are blue, some intensely so. It's all because of light scattering. Snow, and snow-covered or uncompressed icebergs are white because all colors of light are scattered equally by the large particles -- just like milk. On the other hand, the ice in blue icebergs is highly compressed so that gas and bubbles are squeezed out. In that condition, blue light is scattered more strongly than light of longer wavelengths -- just like a blue sky.

A Google search turns up that there are occasionally green icebergs, colored by the algae that coated their underwater part, which then rolled over. We didn't see any of those. Blue was plenty good enough.