A repetitive set of elements Piranesi uses in the prisons are, curiously, related to seafaring. The nautical elements found throughout the plates of the Carceri series are not only a personal connection that Piranesi explores with his hometown Venice, literally a bunch of small islands held together by aqueous roads in the middle of the ocean, but a homepage to the education he received there. It was in Venice that Piranesi was introduced to classical authors such as Livy and Pliny the Elder, whom taught him the love for the wonders that ancient Romans bequeathed.
As a consequence of the fascination for ancient Rome, Piranesi was deeply committed to defend the origins of the Italic civilization and its roots in the Etruscans as opposed to the Greeks. He was supported, among others, by the theories of the Neapolitan philosopher Giambattista Vico (1668 - 1744). In 1744, shortly after his demise and months before the assumed beginning of the imaginary prisons’ illustrations, a third, much enlarged, and completely revised edition of Vico's Scienza Nuova was published. Its ideas are essential to understanding the Imaginary Prisons: the book argues for the alternative lineage of Romans via the Etruscans instead of Greeks, “proving” the autonomy of Rome from Greece.
The nautical elements, therefore, are also a reference to the "true" founding fathers of the Italic civilization: the Etruscans,. Called “pirates" by the Greeks, the Etruscans were exceptional sailors and created a rich repertoire of ornaments derived from the forms of the shells, present here and in plate XV, and later on explored by Piranesi again in Diverse Maniere d'Adornare i Cammini. The artist also benefitted from the "shell mania" of the eighteenth century, a phenomenon similar to the seventeenth-century "tulip mania."
In terms of composition, Piranesi effectively operates one of the most dramatic expansions of the space from the first to the second edition in this plate. The artist multiplied the formerly somewhat flattened background towards the depth of the pictorial space, greatly extending the interior areas inside the building.
He releases the space in the lower half of the illustration by replacing the barred grid below the archway with an open passage that reveals a series of new scenarios. Likewise, in the upper half, countless new areas seem to grow in profundity and intricacy. The second state is also much more populated with human figures, including a procession that takes place in the projected platform between the two sentry boxes. As in other plates, people hang a cloth on the parapet, emulating the Catholic festivals that occurred in Piranesi's time.
The illustration suggests a sense of movement in which the ship, partially represented, glides toward the passageway under the bridge. Ultimately, the clash between the vessel and the architecture seems inevitable.