A dense, pale sky dominates the upper half of Rough Sea, dissolving almost seamlessly into the horizon below. The lower portion of the painting is filled with tumultuous, swirling forms that suggest the movement of waves, rendered in earthy ochres, greys, and muted greens. White, foamy highlights break through the darker masses near the center and left, evoking the cresting of water against unseen rocks or the churning of the sea.

There are no distinct figures or vessels; instead, the brushwork is loose and energetic, with sweeping strokes that blur the boundaries between water and air. The composition is anchored by a darker, shadowy area just left of center, which hints at depth and turbulence beneath the surface. Closer inspection reveals subtle variations in texture, with some areas built up in thick, impasto layers while others are thin and translucent, allowing the canvas to show through.

The overall effect is one of atmosphere and movement, capturing the restless energy of the sea rather than its precise details. In the lower right corner, a diagonal sweep of dark brown paint suggests a shadow or deeper trough in the water. A small, triangular patch of reddish-brown appears near the lower right edge, isolated from the rest of the composition.

The upper left and upper right corners are softly blended, with pale beige and grey tones that fade into the sky, creating a sense of openness at the painting's edges. Hints of yellow ochre and olive green are scattered throughout the lower half, mingling with the greys and browns in loose, irregular patches. Thin, almost linear marks in the foreground create a sense of movement and directionality, contrasting with the broader, swirling brushstrokes elsewhere. Rough Sea is the work of Joseph Mallord William Turner, painted between 1840 and 1845.

The title points directly to the subject—a turbulent seascape—while the absence of narrative or specific landmarks leaves the focus entirely on the play of light, water, and air. The museum's records identify the materials as oil paint and canvas, which Turner manipulates here to create both delicate veils and vigorous, textured passages.