"Thou counterfeit'st a bark, a sea, a wind;
For still thy eyes, which I may call the sea,
Do ebb and flow with tears; the bark thy body is,
Sailing in this salt flood; the winds, thy sighs;
Who, raging with thy tears, and they with them,
Without a sudden calm, will overset
Thy tempest-tossed body."
Shakespeare compares Juliet to a boat in a storm. The comparison is an extended metaphor where he compares her eyes to a sea, her tears to a storm, her sighs to the stormy winds and her body to a boat in a storm.