The Dead Lands of Athas
The Windfire Sea is a heaving sea of viscus, inky-black liquid which undulates and boils with the oppressive heat of a lava caldera. This “sea” is a living portion of the wave of Living Obsidian which covered the entirety of the Ulyan Basin and destroyed it’s people. Why the obsidian which covers the site of this ancient ocean remains in a liquid state, none can say for certain.
Small hills of jagged obsidian have formed from sheets of obsidian crawling over the ground and then cooling and hardening. After thousands of years the thin layers amassed into small hills, standing just over twelve feet high in some areas. The area surrounding the Windfire Sea is extremely hot, and the sea itself boils. The temperature here can reach over two hundred °F, temperatures unbearable for even the toughest elf.
Any person who comes too close to the undulating mass will be in for trouble. The “Living Obsidian” crawls over all matter it comes in contact with of its own volition. Those unfortunate enough to suffer this fate will first be badly burnt and then suffocated to death. Undeath will soon follow.