Armor Class: -6
Hit Dice: 800 hit points (treat as 21+ HD creature)
Attacks: 1 (swallow)
Damage: 8d8 per round
Hoard Class: None
In the post-apocalyptic future, there is an island paradise, one miles off the coast of the mainland that is seemingly untouched by the ravages of the radiations and poisons that have ruined the rest of the planet. This island is called "Pangaea" by the primitive natives who live there. The island -- about 12 square miles in size -- hosts an abundance of flora and fauna which sustains the small civilization that flourishes there. For many generations, the Pangaean people have lived peacefully on this isolated island, never making contact with the survivors roaming the rest of the planet. It is almost as if they have managed to avoid the ravages of the blasted planet's atmosphere, as well as the evils of the world's remaining inhabitants. In a way, they have. The "island" has been actively avoiding such things for millenia.
What the Pangaeans don't know is that their island paradise has formed on the back of the largest creature to roam the oceans -- a gigantic turtle-like monstrosity. This creature (which we'll call "Pangaea" here) is 3 miles wide by 4 miles long. Over untold thousands of years, Pangaea (which is incredibly long-lived) has floated on the surface of the oceans. Its shell has been covered with soil and silt, allowing a flourishing ecosystem to develop. Birds and animals that found themselves on the "island" roosted and build homes. Eventually, mankind found Pangaea, establishing a small community as well. Because Pangaea is fairly inactive, its true nature has never been discovered.
Pangaea's head and legs have remained below the surface of the seas for hundreds of years, which has hidden its true form. Unlike a normal turtle, Pangaea is a water breather, so it does not need to surface for air. Also, the creature's has a very slow-running and efficient metabolism and feeds only once every 10 years or so, eating ocean-dwelling fish and sealife under the surface. The creature's also inactive to a degree, preferring to float on the surface rather than moving of its own accord. Because of this, it's not unusual for the "island" to drift slowly from one location to another. The Pangaeans have come to accept the fact that their island is not truly anchored to the ocean floor, but they have never thought to investigate why this is so. The few visitors who have stopped on the shores of the island may be surprised to find the island gone when they return a year later.
Due to the sheer size of Pangaea, it cannot be easily harmed with conventional weapons. (It'd be like stabbing Rhode Island and expecting it to bleed.) The build-up of topsoil on Pangaea's back is 30 feet deep at its most shallow. Beyond that is the creature's tortoise-like shell. It would take a tach-nuke to get its attention in this way. If a determined mutant were to somehow go underwater and approach the creature from the front, he would encounter a leviathan tortoise head about 300 feet wide. Although this is the "weakest" part of Pangaea, it is also the most dangerous. If the creature does open its mouth, it has begun to feed. The sudden intake of water rushes every living thing into its mouth. Any unfortunate mutant will be immediately swallowed, taking 8d8 hit points of damage per round until he dies in the creature's stomach.
If Pangaea is ever seriously injured, or if the creature is irritated by too much activity on its back (say from an invading force or a population growing out of control), it will decide to "wash off" the infestation, diving to the floor of the ocean where it will lurk for 500 years before resurfacing again. It has done this once before, when it was known by the name "Atlantis."
Mutations: gigantism (to an insane degree), water breathing, natural armor