From NASA is this image of a marine phytoplankton bloom showing as a blue-green swirl off the coast of Argentina. These colors are created by light reflecting from the chlorophyll and other pigments contained within billions of tiny plants (phytoplankton) growing in the surface waters. This bloom is sustained by nutrients brought to the ocean by freshwater rivers carrying agricultural run-off and other nutriends into the ocean.
Image by NASA
Read more about this Marine Phytoplankton image
at the Earth Observatory website.