Coleridge utilizes imagery in "The Rime of the Ancient Mariner" to reveal the deeper theme of imprisonment. At the very beginning of the poem, the sailors' ship seems the embodiment of freedom, allowing them the liberty to sail wherever their hearts desire. The novelty of adventure soon wears off as the men find themselves pulled by a storm into the rime. The ship becomes locked in a field of ice "mast-high" and the sailors quickly realize that they are trapped on the ship, unable to free themselves. As the days on the ship lengthen, the sailors also become imprisoned by their own physical needs--water, and their longing for it, also becomes a prison; the sailors even lose the ability to communicate with one another due to their parched throats. Ultimately, their imprisonment on the ship proves absolute; only death provides release.
The Ancient Mariner also suffers a form of psychological imprisonment for his grievous crime of shooting the albatross. At the end of the poem, the Mariner still mentally exists in the rime, locked within his own confused mind of what is real and what is imagined.