"The Open Boat" is an excellent example of Naturalism. Naturalist literature illustrates the ways that humans are influenced and determined by elements of nature (internal and external) and social/natural conditions. The four men in the boat are at the mercy of the sea (Nature). Only by working together (this could be defined as culture) do they have a chance at surviving nature's indifferent forces. The wood of the boat and the oars separates the men from the icy water. Rowing is their only means of attempting survival, hopeless though it may be.
This notion of nature being indifferent is key to this story. In their predicament, facing the possibility of death, the men in the boat are frustrated at nature's indifference and the senselessness of how nature seems to be toying with and oppressing them.
The act of rowing is their physical engagement with the sea (nature) and this complements their mental frustration with nature. As rough as the seas are, the rowing is a valiant effort; but in terms of nature's indifference and power, the rowing is depicted as being largely futile, with only a spark of hope:
The oiler and the correspondent rowed the tiny boat. And they rowed. They sat together in the same seat, and each rowed an oar. Then the oiler took both oars; then the correspondent took both oars; then the oiler; then the correspondent. They rowed and rowed.
Note the repetition; as if it is an unending or pointless task. Feeling as if they are making little to no progress, the men continue to look for the lighthouse; again, a connection to culture in response to their struggle with nature. The rowing is their physical engagement with nature; the actual struggle. Each took turns rowing until he collapsed in sleep. Rowing is both a glimmer of hope in survival but also a more hopeless delaying of death/drowning. Since they take turns in the rowing, the rowing itself establishes a bond of community and brotherhood: in opposition to the indifference of nature. When the boat is overturned, this brotherhood is not severed completely, but the situation does become more of an "every man for himself." We might say that the community or culture or rowing was their attempt (failed) to tame or overcome nature.