[1] National Gallery of Art curator Adam Greenhalgh writes that the painting possibly references the beginning of World War II, which occurred while Hopper was working on Ground Swell.

The blue-green buoy with brown seaweed is the only dark feature in a scene dominated by bright blues and whites, its clanging bell warning of imminent but hidden dangers.

Cirrus clouds in the sky herald an approaching storm hinted by the dark line of the horizon, perhaps influenced by Hopper's experience during the 1938 New England hurricane the previous year.

Homer's painting was made a few years after the end of the American Civil War, with the crew of the boat optimistically looking to the horizon: in Hopper's work, the scene of tranquility contains notes of peril.

[6] Hopper used a medium-weight plain-weave "Winton" canvas, with a grain that makes it suitable for landscapes and seascapes, commercially pre-primed with a thin layer of cream paint.

In the lecture and the article, Nemerov examines Ground Swell's connections with the political and cultural events of 1939, as well as the personal significance of the painting for Hopper.