The Sea of Mist.
It was a dimension that had gotten more and more inhabitable with each century that passed by, there came a time when people could not even step out and stand at the shore of the ocean without wearing the most expensive toxin-reducing suit to avoid getting ugly blisters on their skin. In fact, even if they were wearing the S-class suit to ward off the toxic fumes, they could not stay outside for long.
As the temperature at the shore of the Sea of Mist was simply heaven-defying. In the afternoon it was too hot, to the point where anyone would feel like they were shedding off a layer of skin and in the night it was so cold that anyone with life within them would feel like they were freezing to death.
