Black Sea Swirls

[25-Jun-25] Beautiful swirls in the Black Sea reflect high primary productivity in upper layers. Deeper layers in the Black Sea are oxygen-depleted, making them largely inhabitable for most marine life. Green colors in the northwestern shelf areas indicate higher concentrations of microscopic algae known as phytoplankton, nourished by nutrient input from major rivers like the Danube. This image was taken by the Ocean Color Instrument (OCI) sensor aboard the PACE satellite on June 25, 2025.