"The color is attributed to a bloom of coccolithophores, phytoplankton with calcium carbonate plates."

A Turquoise Tide: NASA Satellite Captures Spectacular Phytoplankton Bloom in the Black Sea

In late June 2026, satellite imagery from NASA revealed a striking turquoise swirl painting the surface of the Black Sea. The vibrant discoloration, captured by the PACE satellite on June 22, is caused by a massive bloom of coccolithophores—microscopic phytoplankton encased in reflective calcium carbonate plates.

These tiny organisms become visible from space only when they amass in vast numbers. The bloom occurs naturally during the late spring and early summer, as sunlight and nutrient conditions align. When the coccolithophores die, their calcium carbonate shells sink, playing a critical role in the ocean’s carbon cycle by transporting carbon to the seafloor.

Remote sensing technology, like that aboard the PACE satellite, is essential for studying these events where direct water sampling is limited. The phenomenon is not isolated to the Black Sea. Just weeks earlier, on May 27, 2026, astronauts aboard the International Space Station (ISS) photographed a similar turquoise patch in the Bosphorus Strait, which connects the Black Sea to the Sea of Marmara.

Data Sources

• Satellite Image: Acquired by the Ocean Color Instrument (OCI) on NASA’s PACE satellite (June 22, 2026).
• Astronaut Photograph: ID ISS074-E-619520, captured by the Expedition 74 crew (May 27, 2026).