As the close-up image shows, an eddy is outlined by a milky green phytoplankton bloom. Eddies are masses of water that typically spin off of larger currents and rotate in whirlpool-like fashion. They can stretch for hundreds of kilometers and last for months. As these water masses stir the ocean, they can draw nutrients up from the deep, fertilizing the surface waters to create blooms in the open ocean. Other times, they carry in nutrients spun off of other currents.
Or an underwater Norway spiral.