The above question requires a personal answer, plus you didn't show the poem it refers to. For these reasons, I can't answer this question for you but I'll show you how to do it.
To answer this question, you will:
Read the entire poem.
Pay attention to the descriptions of the sea that the poem provides.
Identify the line that caught your attention the most.
This line should be the one you liked the most, either for the detail about the sea or for the author's use of words.
In that case, to help you find your favorite line, you can search for articles that analyze that poem and show the meaning of each line in more depth.
More information on descriptive language at the link:
Use complete sentences throughout the assignment and table. Provide comprehensive explanations with a minimum of 4 sentences for each rationale section. The table cells will expand as you type. Be sure to proofread and edit carefully for correct grammar and spelling.
