The waters of the Barents Sea off the northeast coast of Norway were bright with a green and blue bloom of phytoplankton on September 4, 2009, when the MODIS on the Aqua satellite captured this image.
Phytoplankton are tiny marine organisms that, much like their land-based plant relatives, use sunlight to convert water and carbon dioxide into food. Some species of phytoplankton are coated with scales of calcium (chalk), which can turn the water electric blue. Chlorophyll and other light-capturing pigments in others give the water a deep green hue. The proliferation of many different species in various stages of growth and decay can provide many nuances of color.
In northern waters, these organisms are starved for sunlight much of the year, but during the summer months, they explode in colorful blooms such as this one.