A recurring theme in Jack London's work is the dichotomy between the wild world and civilization. London repeatedly examines both humans and animals who move between these two worlds and are forced to adapt themselves to the changed conditions and expectations they encounter.

Van Weyden, in The Sea Wolf, is a kind of human analogue to Buck in The Call of the Wild. Like Buck, he has lived a comfortable life in the ordered, civilized world, and he is suddenly thrust into a rough, wild mode of life in which the old rules no longer apply. On Wolf Larsen's ship, physical force is the dominant factor controlling the interactions of men. Van Weyden's status on land as a "gentleman" who lives by his inherited wealth is suddenly canceled. Fortunately for him, he is able to adapt, and though he's appalled by the brutal behavior of the men on the ship—especially Larsen himself—he knows enough not to antagonize the others, and eventually becomes a physically self-sufficient man in a way he had never been before.

Underlying this dichotomy between civilization and brute force is the issue of what constitutes moral behavior. Wolf Larson is a Nietzschean figure who regards of himself as one "beyond good and evil," to whom the moral code of the civilized world does not apply. London poses the question of whether man has the right to reject the morality of tradition and religion and to act as if he were a kind of god himself. The episode in which Mugridge is beaten up is a significant point in the story, because Larsen is shown just watching, calmly smoking and doing nothing to intervene despite the fact that the beating was provoked by Mugridge's criticism of Leach, who had the boldness to hurl a stream of invective at Larsen. Larsen is an ambiguous figure in London's moral universe. He is not the kind of totally evil character London shows us in, for instance, Beauty Smith, the dog-fight manager in White Fang. One might ask the central question of whether Larsen, despite his amoral and brutal nature, is the pivotal force in van Weyden's life, in having taught the latter what it takes to survive on one's own in the world.

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.