In this highly abstract seascape, John Marin painted an image striking in its stability, simplicity, and clarity of design. Painted on Deer Isle, Maine, Grey Sea shows the crests and waves of the Atlantic. In a slightly earlier watercolor, Marin had emphasized the frothing waves crashing on the shoreline. He developed the image further in this composition by capturing the underlying rhythms and motion of the ocean. The painted borders that form an internal frame enclosing the image emphasize the force of the waves. Marin painted this internal frame in simple, flat watercolor strokes, roughly drawn, echoing the turbulent, raw quality of the ocean.
Duncan Phillips considered this work one of the cornerstones of his Marin unit. He often included it in exhibitions and in lectures. Writing in The Phillips Collection’s 1927 Bulletin, Phillips declared Grey Sea, to be "one of the greatest watercolors ever painted." In his article, Phillips went on to write:
The element of unfathomable Ocean...Surf charges over rocks...shot up in a shaggy elemental explosion. The waves are opaque, sombre and unutterably strong and deep.... The Infinite starts at the horizon's edge and there is something inexorable in the sky—in the straight severe line of cloud contrasted with the thunder and rage of the sea.