La mar is Spanish for "the sea". The sea can be seen as a symbol of life itself in this story, as both good and bad come from it. Santiago alludes to this at more than one point during the story as well. On good days, the sea provides him with many fish. He then sells the fish to maintain his livelihood. He sells them for money, and uses money to provide for his modest needs. Other times, he cannot catch any fish. These bad days result in hard labor without reward. So, I see the sea as symbolic for life; some days are very good to us, while other days are not. However, we are part of life, and life is part of us, just as the sea, or "la mar", was the biggest part of Santiago's life. For better or worse, we must get through each day, hopefully catching the proverbial fish, rather than letting it get away.