NASA's PACE satellite captured the Black Sea turning vivid turquoise on June 22, 2026, during its annual phytoplankton bloom. The striking color resulted from massive numbers of coccolithophores visible from space. An astronaut aboard the International Space Station had earlier photographed a similar bloom in the Bosphorus.
The Black Sea lies between Europe and Asia. It normally appears dark but transforms every spring and summer when coccolithophores multiply. These microscopic organisms have reflective calcium carbonate shells that scatter sunlight and create a milky blue hue.
On June 22, 2026, the PACE satellite's Ocean Color Instrument recorded the seasonal display across large areas of the sea. The bloom also extended into the Bosphorus, the waterway through Istanbul. An astronaut on the International Space Station captured swirling currents there on May 27, 2026.
At other times of year diatoms dominate and darken the water instead. Satellite observations help scientists monitor marine ecosystems where direct sampling is difficult. The phytoplankton also absorb carbon and contribute to long-term storage in the seafloor after they die.
