Caused by the excessive introduction of nutrients to the marine environment, eutrophication remains one of the principal threats to the biodiversity of the Baltic Sea. It is driven by a surplus of the nutrients nitrogen and phosphorus in the sea: this nutrient over-enrichment then causes elevated levels of phytoplankton. The blue/green swirls that can be observed on the images are cyanobacteria or phytoplankton blooms that were captured by the Landsat 8 satellite (courtesy of USGS) and enhanced through our pre-processing maneuver. The maximum area of 125,000 km2 covered by cyanobacteria blooms was observed on August 14, 2015.