Lurking in the lower left corner are pink and red swirls usually identified as the eponymous sea monsters.

[6] Critic James Hamilton speculates that the mist may hide a steam driven paddleboat being consumed by giant fish[2] or whales, which were the subject of many of Turner's later works.

[8] Other sources claim that the monsters really are just that: Michael Bockemuhl suggests that the swirls combine to form a single behemoth with large eyes and open mouth that is swimming towards the observer.

Gunnar Schmidt claims the painting has two zones—the warm sunny sky, and the cold dark water—and that at their interface is a mass of drifting steam that has particles and vortices but no shape or limit.

A paper in the Journal of the Royal Society of Medicine draws a connection between these figures and Turner's possession of acetate of morphia (a drug related to morphine), possibly used for the treatment of a toothache.