What specific situations are created in the novel? How?
"Situations"? That's a bit nebulous, but I'll try:
1. Man vs. man: Santiago is a fisherman on a dry streak, and he's been the target of the younger fishermen. Santiago fishes in the Biblical sense: with nobility and respect for the fish ("his brothers"), but the young fishermen fish for money and killing. They have no art or respect for their prey.
2. Man vs. himself: the Old Man Santiago is fighting against his body and mind to endeavor one last great catch. He ventures far out and must battle the elements, his aging body, and fear of failure and death in the epic struggle to land the marlin.
3. Man vs. animal: Santiago battles the marlin, but it is a healthy battle, one waged with respect. Santiago hates the sharks who kill out of mindless instinct. To Santiago, sharks are scavengers; they do not possess the grace and beauty of a big game fish.
4. Mentor and disciple: Santiago's goal is to become a fisher of men: to teach a man to fish--namely Manolin. The young boy looks up the old man as a paragon of humility and grace. Santiago become's an emblem of suffering by the end in order to teach others to endure humbly.