One of the major themes in "The Sea-Wolf is that man is not an island. Larson's approach to life is on of dogged individualism. He believes in the strength of man and does not plan on giving in to anyone or anything. He is even willing to die and have everyone else die rather than give in. Due to his philosophy on life he is destroyed in the end. Individual strength and will are of course, to an extent a good trait, but as we learn in the novel from London cooperation, compromise, and sharing the load will get the job done faster and sometimes better. Humphrey van Weyden is a man who begins as an elitist and ends up as a courageous man who overcomes the bully Larson. Humphrey is rescued from death when Larson saves him from a ship wreck and he takes that second chance and makes the most of it.
A secondary theme is the love of life versus the love of materialism. Larson is all about materialism and Humphrey is an "idealist" who believes that a man's life is a worth more than material things.