The statement that best expresses the theme is: who we are determines how we view the world.
At the beginning of the poem the sea is described according to how the maiden sees it. She considers it beautiful like a meadow with people singing. To the sailor, on the other hand, the sea embodies evil because he has witnessed hard situations and he has probably seen people die because of the tides and the sea "hatred". Depending on the characters' life experiences, they see the sea as a natural beautiful thing or as a source of pain.