To the north and east of the Falkland Islands, shown here just to the left of center, the South Atlantic Ocean is vibrant with color. This true-color image from November 13, 2001, shows the waters in the South Atlantic swirling with the blues and greens that indicate massive amounts of microscopic marine plants called phytoplankton. The variety of colors can be due to varying concentrations and types of phytoplankton and the chlorophyll and other pigments they contain. The bright blue swath to the east of the Falklands is most likely a blue-green algae called Trichodesmium or else coccolithophores, which make limestone (calcite) shells around themselves using dissolved carbon from the ocean water. Very dark green areas (almost purple in places), such as the area directly north of the Falklands, could be caused by extremely high levels of phytoplankton--so much light being absorbed by chlorophyll that the water appears dark.