How the Ocean Works

The ocean is sorted into layers by density, and very little moves between them without energy. Where wind, tides and winter cooling return nutrients to the sunlit layer, production follows. In the Gulf of St. Lawrence in summer, the cold water is the layer in the middle.

Share
Satellite view of a rugged island coastline, with turquoise shallows fading into deep blue ocean.
Photo by NASA / Unsplash

Originally published . Substantially updated .