This image from the Moderate-Resolution Imaging Spectroradiometer (MODIS) shows black water off the coast of Florida on January 30, 2002. In late March 2002 a diver investigating the water discovered dead and dying sponges and coral—an indication that the discoloration may be the result of a toxic phytoplankton bloom, which sometimes kill sponges before other marine species.
Image by Jesse Allen, Robert Simmon, and the MODIS science team.