Baltic Bloom

June and July brings blooming phytoplankton to the Baltic Sea, seen here in late July 2025. On-the-water measurements show that much of this bloom was cyanobacteria, an ancient type of organism among the first to process carbon dioxide into oxygen. These organisms thrive in nutrient- and nitrogen-rich waters. Here, they mark out the tides and currents that mix the Baltic. Zoom in on the full image, and you’ll see dark, nearly-straight lines across the swirls; these are the wakes of boats. (Image credit: M. Garrison; via NASA Earth Observatory)