The title may remind the reader of an old man, who's celebrating his story of voyages and adventures by ship. Another important element is represented by the structure of the poem, which is very likely to follow a rhyming pattern.
Since the second and third part aren't taken into consideration, it is hard to describe what happened before the fourth part. By the way, the examinated part begins with a dialogue by the guest, who is expressing his apprehension towards the weak aspect of the mariner. The sailor, consequently, reassures the wedding guest, being his survival a miracle, as many other sailormates died. The mariner's whole dialogue is a description of the fury of the sea and of several animals and colours, which are seen as spiritual signs.
The fourth part is set up by 15 stanzas (9 quatrains, 4 pentametres and 2 sestets). The irregular structure reminds to the reader the waves of the ocean, which break up against a ship with a changing power, especially during sea storms. The rich punctuation, at the end of almost each line, aims to guide the reader within the poet's imagery, meaning that the pauses convey a sense of rhythmic slowness. There are several repetitions, in accordance to the typical scheme of a ballad ("I fear thee... I fear... I fear thee"; "alone, alone, all, all alone/alone"; "and they all dead did lie/And a thousand thousand slimy things"). The third line of the first stanza is enriched by closed vowels, in order to highlight the sense of spontaneous fear that the guest feels. The third stanza is full of diphtoungs which convey the image of a powerful sea and an astonishing sound. The repetition of the word "I" throughout the 4th, 5th and 6th stanza emphasizes the importance of the salilor's actions, which are almost always perceptive and defensive actions ("I looked upon", "I looked upon", I looked to", "I closed"). In the 27th verse, there's a chiasmus ("for the sky and the sea, and the sea and the sky"), which is important to describe the rapidity of the events, from the sailor's point of view, and to influence the reader's imagery; in fact, both the sea and the sky are the utmost forces in Nature. In the 9th stanza there are several elements which highlight the concept of supernatural made real. First of all, the abstract words used to describe the sailor's thoughts and perceptions highlight the idea of spirituality ("curse", "Hell", "on high", "curse in a dead man's eye"). The 38th line, on the other hand, has a concrete connotation, in order to add realism to the overall imagery ("seven days, seven nights, I saw that curse"). The 13th stanza has a similar function: colourful images ("shining white... Blue, glossy green, and velvet black") are next to supernatural images ("and every track/ Was a flash of golden fire").