John Masefield's poem "Sea Fever" is one of the most popular of all lyrical poems.  The poet's imagery makes the reader feel as though he is at the helm of the ship along with the narrator.  The narration is first person point of view with the narrator being the seaman who loves his life. 

His repetition of the first line of each of his stanzas emphasizes the theme of the poem.

I must go down to the seas again, to the vagrant gypsy life...I must go down to the seas again, for the call of the running tide...I must go down to the seas again, to the vagrant gypsy life...

The narrator is driven to the sea life and all its excitement and adventure.

Each verse describes a different scene at sea.  He tells the reader that the life can be lonely steering the ship at night with the wind blowing the sea mists in his face till dawn comes.

In the second stanza, the call of the sea goes deep in the heart of the sailor. All he wants is a windy day with sea foam blowing and the seal gulls crying above.

The final stanza describes the sea life like a gypsy who wanders all over the world.  With whales and gulls and wind, he loves to share the tales and laughter with a fellow sailor.

In the last line of the poem, the word "trick" is used.  To the sailor, a trick was a watch at sea. It is four hours "on" and eight  hours "off" watch.  This schedule is a sailor's day which is followed even today.  The last line refers to the sailor wanting to sleep soundly with pleasant dreams at the end of his long shift on watch or at the helm of the ship.

And quiet sleep and a sweet dream when the long trick's over.