Like Nick Adams, Hemingway found nature to be the best escape from his troubled world.  In fact, Nick Adams is probably the most autobiographical of Hemingway's characters.  It's no accident that Hemingway describes the flight of a kingfisher in Big, Two-Hearted River.  The fisher-king tradition is used by many authors to signify one or more characters seeking renewed health through a quest (for the holy grail for example).  In this case, Nick renews himself through nature-particularly through the river.

When reading Big, Two-Hearted River, it's important to recognize Hemingway's many allusions to creation.  For example, after Nick's finished building his tent, he assesses his situation, and calls it "good." In this way and others, he mimics the Old Testament account of creation.  His "good place" is almost a self-created heaven of sorts. 

Hemingway, not believing in God of course, relied, like Nick Adams, on making his own "good place," finding for himself an escape from the darkness of reality.  Hemingway believed that this self-creation was the only way man could get through life.  Even the short sentences the author uses suggests Nick's attempt to control things for himself, not relying on others.