Answer: Nature is indifferent to humans.
The story's dominant theme is that nature is indifferent to humans. The survivors are desperate to be rescued, and to survive their ordeal. However, the soon realize their insignificance in the face of nature's forces. Towards the end, when some of them are able to survive, they feel they now understand nature. What they understand is that nature is inescrutable and indifferent to humans, and that we will never be able to control it or predict it.