According to Humanities360, John Masefield spent a lot of time on the sea. This would explain his familiarity with seafaring life, and it also means that the poem could be autobiographical, and the poet himself may want to return to the sea.The poem begins with the line, "I must go down to the seas again, to the lonely sea and sky." This instantly sets a tone of longing, with the "I must." The "lonely sea and sky" seem to be an enchanting pull for the speaker, who may feel the need to escape from the life he lives and live a life of contrast on the sea. This is emphasized in the third stanza, where the speaker says he must go back to "the vagrant gypsy life."
The images that the speaker lists suggest that he has intimate experience with the sea. He talks of the sensations of being on the sea, such as "the flung spray and the blown spume," in an effort to evoke the feel of the sea on the reader's face. The poem gives off a sense of happiness that the speaker derives from the sea life and features images and messages of longing. With the jaunty rhythm of the poem and Masefield's AABB rhyme scheme, the poem has been said to sound like a dance when read aloud, and as it picks up steam, it could almost be called feverish, just like the "sea fever" the poem is about.Learn more about Poetry