Icebergs in the Antarctic area sometimes have stripes, formed by layers of snow that react to different conditions. Blue stripes are often created when a crevice in the ice sheet fills up with meltwater and freezes so quickly that no bubbles form. When an iceberg falls into the sea, a layer of salty seawater can freeze to the underside. If this is rich in algae, it can form a green stripe. Brown, black and yellow lines are caused by sediment, picked up when the ice sheet grinds downhill towards the sea.
Icebergs were photographed 2008 by Norwegian sailor Oyvind Tangen, on board a research ship around 1,700miles south of Cape Town and 660miles north of the Antarctic.
More beautiful photos of icebergs can be found here.