In the poem, "A Sailor's Life," McCann, an Irish poet, mirrors his world, his culture, for that is what he knows best. Good writers pen their works through their own experience and that experience is framed within one's culture (one's environment, traditions, values). Poetry, even perhaps more than novels, allows the poet to express that culture. Therefore, Mccann states that as a sailor, he was "Jazzing and living around the waterline." Life for a sailor is focused on all aspects of the job that carries over into a whole existence. McCann tells us himself that his poetry is based upon his personal experiences and reflect his world.
Poets have different reasons for writing about their cultures, but among the primary ones are to record the elements of that culture for all people to read and grasp an understanding as well as an outlet for emotion. Poets usually write as an outlet or reaction to events in their lives--personal, local, state, federal, national events. A prime example is the outpouring of poetry from all over the world in response to the attack on the World Trade Center on 9/11. Those poems record the event, but from different points of view and different cultures around the globe.
Culture includes ideas, traditions, types of food, anything considered taboo, belief systems, values, religion, and even groups as specific as nail technicians and housewives have a particular culture particular to them. Some or alll of these elements will appear in a poem where culture is the focus. See the links below for more ideas. Good Luck!