The first clue is the title. "The Return" is immediately understood to refer to the return of Ivan and Andrei's father after a twelve year absence, but such a connection is a blatant deception to hide a hard truth about the world around us; a truth that may only be revealed by participating in Ivan and Andrei's journey of self-discovery: Every journey has an end. This describes the cycle of life and death in nature. In this metaphor, the father is nature's caustic envoy. His instruction, discipline, intimidation, force, violence, and love educates and prepares the boys to live and thrive in an untempered world that has the power to destroy man's temporary splendor.
The visuals and shots complement the life cycle. The days of the week demarcate the action of the film, ending on the day it began. The camera often cuts to different perspectives in such a way to measure distances. Each "tower" has both a shot at the base and at the very top. After Ivan is left alone on the road, we see the car traveling in the far distance. We see a dead bird, and fish out of water. Ivan's defiance is the response to the world's neglect. Who is he really talking to when he pulls out the knife and proclaims, "I could have loved you, but you're terrible!"? He is speaking to the world he is witnessing first hand.
As a final lesson, Ivan's father sacrifices himself when Ivan threatens to jump off the island's tower. The boat on which the boys lay his corpse sinks and we are reminded of the opening shot of the sunken dingy to which we have "returned".