And so, the end had come. Countless wars and cataclysms ravaged the world we once knew, turning the entire planet into a sorrowful, lifeless wasteland. Scattered remnants of humanity turned toward the only places still capable of sustaining life — the oceans. Yet peace would not be theirs. A shattered balance in nature had awakened ancient beings from the shadowy depths, creatures that were never meant to see the light of day.
The vast watery expanses, once humanity’s last hope, soon teemed with unknown and deadly threats. For the umpteenth time in its long and troubled history, mankind had to relearn the art of survival — this time in a world ruled by wild, untamed marine nature.
From this necessity emerged the concept of pirate cities — enormous floating fortresses, shaped like sea monsters, built to intimidate the creatures of the deep and ward off potential attacks. To this day, these cities drift across the horizon in great iron shoals, chasing the ever-distant promise of a better tomorrow.
Water has become the new master of this world — an untamable force, at once the giver of life and the bringer of death. It sets the rules now, offering both the faint hope of survival and the looming certainty of doom.

This is my concept for post-apocalyptic world. I had occasion to have a little fun with environment.