Abyss Zone

Place of End and Creation: The Abyss Zone is a sealed area of the unnamed island Popora inhabits. It is where the Straw Hat Pirates confront the Evil Guardian in One Piece: Unlimited Adventure.

Geography
The Abyss Zone is only accessible via the Cave Zone. From its dark, swirling entrance, it leads down a winding stone path to a single circular platform made of bluish grey, cracked stone. The platform is covered in markings of blue light. The platform is surrounded by darkness, with wisps of green and yellow light swirling around it. After the Evil Guardian is defeated, the platform loses its blue markings.

Enemies
The only boss in the Abyss Zone is the Evil Guardian, followed by his transformation to become the Evil Master Beast.

Past
When Sealed used his power to restrain the Evil Guardian, he sealed the monster away in the Abyss Zone.

One Piece: Unlimited Adventure
Over the course of the game, the Straw Hat Pirates released the island's seals and opened the entrance to the Abyss Zone. When they and Popora came upon the Abyss Zone to fight their final battle, the orb showed them a memory of Sealed sealing away the Evil Guardian and leaving Popora behind. They walked to the central platform, and above them, the Guardian broke free from his chains and dropped down below to face them. The monster shouted, and Popora jumped to attack him, hitting him on the head with his hammer. Unfazed, the Evil Guardian knocked him away, but Luffy caught Popora. The crew promised to vanquish the evil force after Popora spent so long protecting his island.

They fought and defeated the Evil Guardian. Usopp was underwhelmed, but Luffy warned that the battle was not yet over. Yellow light swirled through the air and carried with it the hatred and greed of all of those who has sought the island's treasure. The light concentrated into the Evil Guardian, transforming into the grotesque Evil Master Beast. Consumed with rage and hate, the monster fought back stronger. The crew fought ad defeated it, and the Evil Master Beast collapsed in on itself before shattering. The orb showed a memory of Sealed, hoping that someone would someday free Popora. The crew stood on a now lightless platform and Popora cried out in victory. The cave began to collapse, and they all escaped to the Plain Zone.