I imagine that in a dystopian future, humans will have failed to address the environmental consequences of their actions. The outcome being sea levels rising to the point that entire metropolitan civilizations would be drowned beneath the water. The few individuals who survive would have been a part of the elite which had exploited nature for capitalistic gain and would have had to money to adjust to a new way of life. Regardless of their social class they wouldn’t be able to escape permanent darkness owing to the heavy layer of junk and plastic waste that covers the water’s surface. The once-thriving cities that previously stood as monuments to human development and success will become nothing more than forgotten ruins, drowned and lost to the depths of the ocean.