The Underworld is a location place in Hercules. It is the home of Hades, Lord of the Dead.
Locations in the Underworld
This river carries the dead to the Underworld where they will spend the rest of eternity in either the Elysian Fields if they were good or Tartarus if they were evil. In the episode of the animated series Hercules and the River Styx it is revealed that the river is also a Goddess that only reveals herself to those who wield Poseidon's Trident. It is also revealed that the river marks the border of Hades' domain.
Technically Styx is in fact a nymph, and will live for as long as her river flows.
Tartarus is the deepest, darkest and most sinister area of the Underworld. It is here where the souls of the wicked and evil are sent and it is also the place where Zeus imprisoned most of the Titans and a giant Cyclops after he ended their reign of destruction. It is a dark and ominous dungeon-like place with a large ocean located above it, within the ocean lies a few jagged rocks rising from its floor, their is also a small island filled with jagged mountains where the Titan Prometheus is imprisoned and each day a giant eagle comes to eat his liver.
The final resting place for the good and the heroic. It is a paradise filled with beautiful valleys and temples. This part of the Underworld is protected by Zeus. Hades attempted to win it from Zeus in a bet in the episode Hercules and the Driving Test, but he lost.
Kingdom Hearts series
The Underworld appears in Kingdom Hearts II as a location in the world of Olympus Coliseum. In the game Hades, with the help of Pete plans to kill Hercules by re-opening the Underdrome, a violent and dangerous Underworld coliseum that was sealed away by Zeus for its savagery. In order to do this Hades summons a powerful fighter from the deepest pits of the Underworld named Auron to fight Hercules in the Underdrome and kill him, however Auron refuses and is nearly defeated by Hades but he was able to escape thanks to Sora. Later on Hades kidnaps Megara and imprisons her in the Underdrome's lock which Sora unsuspectingly opened which caused the Underdrome to be re-opened.