Plankton find a rich feeding ground in the cold waters lying off the Namibian Desert coast. They have found a narrow corridor of cold, nutrient-rich water in the Benguela Current along the coast. Just a few kilometers out to sea, the warmer waters of the Atlantic do no support the plankton. The band of clouds across the top right of the frame has been created by the interaction of the colder waters of the current and the atmosphere, so the boundary between the cold coastal waters of the Benguela Current is clearly evident to the space observer.
It is one of the subtle wonders of the fragile earthly environment that plankton, and the fish that feed on them, should find such attractive feeding grounds sandwiched between the Namibian desert, one of the driest places on earth, and the warm, nutrient-poor waters of the central Atlantic.