A ship is shrinking toward the horizon, and a figure on the shore is falling apart in the weather. The sonnet opens on the storm alone: "Wild is the foaming Sea! The surges roar!" Only at line 9 do we learn what the storm is for, when the speaker cries "Phaon! return!" The lover has sailed away. The poem never names the speaker in these lines, but readers who know the old legend of Sappho and Phaon will hear it echoing here. The number in the title suggests the sonnet belongs to a longer sequence. Its central idea is that the sea's fury, however terrible, is only a feeble copy of what rages inside a heartbroken person.
The form supports that idea. This is a Petrarchan sonnet, with an octave rhyming ABBA ABBA and a sestet rhyming CDCDCD. The octave's A-rhymes, "roar," "more," "shore" and "pour," keep returning to the same booming vowel, like waves breaking on one spot. The B-rhymes, "round," "rebound," "sound" and "wound," add to the pounding. In the sestet the rhymes alternate and the pattern loosens, and the voice changes with it. The turn comes exactly where the form expects it, at "Phaon!" The lines stay in steady iambic pentameter throughout, so the meter holds even while the speaker seems to be coming undone. The exclamation marks, "Ah me!" and the pleading "O!" do the work of the frenzy.
The imagery of the octave builds a violent landscape out of sharp, hard words. The lightnings are "livid" yet "nimbly" darting, as if they were quick-footed. The rock is "rent," and the waves "angry." The most delicate detail is the "less'ning bark," where even the clipped spelling seems to shrink the ship as it recedes. Then the scene moves inward. The shore "trembles," the speaker's "storm-drench'd limbs" are wounded by "flinty fragments," and the "billows pour" over her "bleeding breast." Her body and the coastline start to merge, and the sea becomes an attacker. Her promise that her cries will be "Loud as the blast" is the first sign that she means to compete with the storm.
The sestet reverses the relationship. She asks the winds to "waft the strain" to the departing ship, which makes them messengers. The verb "waft" is oddly gentle for a gale, and "strain" can mean both a song and a struggle. In the same breath she turns on the waves, calling them "barb'rous," telling them to "forbear," and warning them not to "Taunt" her or "feebly emulate the soul's despair." The sea is no longer a monstrous enemy. It has become a clumsy mimic and a rival who cannot keep up. The vocabulary also moves from the physical "limbs" and "breast" to the mental "brain" and "soul," so the real drama is placed inside her.
The closing lines bring back the opening phrase, but changed. "Foaming Sea" in line 1 was a proud announcement of wildness. In line 13 it is "foaming seas," placed in a list with "howling winds," and they "in vain / Assail the breast, when passion rages there." The word "in vain" lands on the rhyme with "strain" and "brain," so it echoes the pleading and the thinking that came before. The storm she began by describing is the same one she dismisses at the end.
There is a neat paradox in this. The speaker can only prove that the storm is weaker than her feeling by first making it vivid and fearsome. The octave's imagery is so strong that the final claim feels like a bold wager, and the poem wins it by sheer force of voice. That is much of its significance. It takes the familiar picture of a storm mirroring the mind and quietly turns it around, so that the mind outdoes the storm. It also gives the grieving speaker real power. Her suffering is not a passive collapse but a force that talks back to the elements, and the strict sonnet form shows that this intensity can be shaped as well as shouted.