Edward Hopper’s lifelong enthusiasm for the sea developed when he was a boy in Nyack, New York, then a prosperous Hudson River port with an active shipyard. Years later, in 1934, he and his wife built a house and studio in South Truro, Massachusetts, where he produced a number of oil paintings and watercolors manifesting his avid interest in nautical subjects.

Despite its bright palette and seemingly serene subject, Ground Swell echoes the themes of loneliness and escape typical of Hopper's oeuvre. The blue sky, sun-kissed figures, and vast rolling water strike a calm note in the picture; however, the visible disengagement of the figures from each other and their noticeable preoccupation with the bell buoy placed at the center of the canvas call into question this initial sense of serenity. The lone dark element in a sea of blues and whites, the buoy confronts the small catboat in the middle of an otherwise empty seascape. Its purpose, to emit a warning sound in advance of unseen or imminent danger, renders its presence in the picture ominous. The cirrus clouds in the blue sky—often harbingers of approaching storms—reinforce this sense of disturbance in the otherwise peaceful setting. Although Hopper resisted offering explanations of his paintings, the signs of impending danger here may also reference a more severe disturbance: during the time that Hopper worked on Ground Swell, from August to September 15, 1939, World War II broke out in Europe.