This satellite image shows the rising of hydrogen sulfide to the surface of ocean waters off the coast of Namibia. The toxic gas robs the water of oxygen, leading to large fish kills. Strong ocean currents sweep nutrient-rich water to the sunlit surface of the Atlantic Ocean. The supply of nutrients allows phytoplankton to proliferate. When the large phytoplankton blooms die, the plants sink to the ocean floor, where bacteria break them down. The anaerobic bacteria that complete the decay process release toxic hydrogen sulfide into the ocean. As it bubbles to the surface, the hydrogen combines with oxygen to form water molecules, leaving solid, white sulfur. White sulfur scatters light, resulting in the blue-green color seen at the center of the image. This particular eruption surrounds Walvis Bay and stretches north along the Skeleton Coast and south to the orange dune fields of the Namib Desert. The Moderate Resolution Imaging Spectroradiometer (MODIS) flying on NASA's Aqua satellite captured this image on July 25, 2007.