Black Sea turned turquoise, thanks to a phytoplankton bloom

The Black Sea isn’t black, and it’s not usually turquoise either. But a huge bloom of phytoplankton has illuminated it — and the connected Bosporus and the Golden Horn of Istanbul — with beautiful swirls of milky blue-green.

This aquatic artwork appears every summer, but this year’s bloom is one of the brightest since 2012, according to Norman Kuring, a NASA scientist. It’s so bright, it can be seen from space, New York Times writes.

NASA created this composite image of the bloom with data and satellite images on May 29. It has gotten brighter since and appears to be nearing its expected peak, around the summer solstice. After a particularly luminous weekend, thousands of people began talking about the opaque, jewel-toned water on social media.