A large phytoplankton bloom fills Skagarrak, a gulf of the North Sea north of Denmark’s Jutland peninsula, and spills into the North Sea on the west and Kattegat on the east. Phytoplankton are microscopic plants that can form large blooms near the ocean’s surface. In satellite imagery, the blooms are visible as bright blue and green swirls in ocean water. This image was captured by the <a href="http://modis.gsfc.nasa.gov" target="outlink">Moderate Resolution Imaging Spectroradiometer</a> (MODIS) on NASA’s <a href="http://aqua.nasa.gov/" target="outlink"> Aqua</a> satellite on June 1, 2004.Skagarrak’s inverted “v” is bordered by Norway, top left; Sweden, top right; and Denmark, lower center. Airplane contrails streak over the North Sea west of Denmark, and a thin plume of smoke is rising from a fire, marked with a red dot, in Jutland. Sensor: Aqua/MODIS. Data Start Date: 6/1/04.