Lord George Gordon Byron's poem "Apostrophe to the Ocean" is actually one long literary device called an apostrophe. Not to be confused with the punctuation mark, an apostrophe is a form of figurative language similar to personification, but the difference is that in an apostrophe, the writer or speaker is addressing the inanimate object or abstract concept as if it were an actual present character. Dr. Wheeler gives us the simple example from Shakespeare's King Lear: "Oh, Death, be not proud" ("Literary Terms and Definitions: A"). Since the speaker is literally addressing death and commanding it not to be proud, we can see how this is a perfect example of an apostrophe.
Byron's poem is one long apostrophe in which the speaker praises the ocean as if it were a real person who can listen to his praises. In praising the ocean, the speaker remarks on its beauty and even its dangers and its terrors. Even though the ocean is something mankind has learned to sail upon, the ocean actually controls mankind, leading to many shipwrecks and deaths: "The wrecks are all thy deed." It is because the ocean is full of such beauty, mystery, and danger and so able to kill that the speaker loves the ocean. Byron portrays his ideas and themes in the poem using many literary devices, particularly parallelism and imagery.
A writer creates parallelism by creating similarities in words and grammatical structures. There are lots of different types of parallelism. One form of parallelism is called tricolon parallelism, which simply means an author has used three grammatical structures to create parallelism (Dr. Wheeler, "Schemes"). We see an example of tricolon parallelism in the very first stanza:
There is a pleasure in the pathless woods,
There is a rapture on the lonely shore,
There is a society where none intrudes.
We can see through the repetition of the phrase "there is" three times that this is a perfect example of tricolon parallelism. More interestingly, the verb "is," which is the singular, present tense form of the verb to be is used to express a state of being. Hence, in opening the poem with this tricolon parallelism, the speaker is establishing himself as being at one with his subject matter, which is the "deep Sea." It could even be argued that the use of the number three in creating tricolon parallelism has significant symbolic meaning. Three is a divine number, used repeatedly in theological concepts, such as in the divine trinity. Hence, it can be argued that in using the number three, the speaker is connecting the ocean with the divine trinity, with his religion--the speaker worships the ocean.
When we speak of imagery, we're referring to any word or phrase that conjures up a mental image in the reader's mind. Images will specifically relate to the five senses--touch, sight, taste, sound, and smell--because only things relating to the five senses can be considered tangible, things we can experience and see; all other words are abstract concepts. Byron uses very vivid imagery to express his themes concerning the ocean, such as the ocean's beauty and terrifying power. Images such as "deep and dark blue" help capture the beauty of the ocean. Images like "bubbling groan," and "grave" help capture the theme that the ocean is a terrifying deathtrap that has total control over man.
To learn more about apostrophe, check out this video: