In The Old Man and the Sea what does the sea symbolize?

The lions in Santiago's dreams represented his lost youth and his decreasing strength. For instance, when he needed strength on his long and strenuous voyage he thought of his dreams of the lions, and of them playing on the beach without a care in the world. With this in his mind it seemed to make him stronger and gave him the endurance to continue. The lions could also symbolize pride. Like the lions Santiago had pride. He was proud of his fishing skills. He was able to keep his lines straight and at varying levels to improve his catch of fish. He was better at this than the younger, richer, generation. Santiago knew however, that too much pride was not good. It could lead to feelings of arrogance and a know it all attitude. He was humble simultaneously with being proud. For instance he knew that he depended upon other people for food and other sustenance. Once the weather was going to turn cold Manolin was planning to bring Santiago shoes, clothes and a blanket.