Tartarus
The Underworld is the Greek afterlife ruled my Hades. Everybody who's Pagan, and in Greece end up in the Underworld when they die unless they are in some other kind of group, like the Amazons.
There are entrances into the Underworld around Greece, like swimming to the bottom of the Alcyonian Lake, or through some caves. Or Hades just opens the earth and comes out. Some of the entrances lead to the river Styx that has to be passed before getting into the Underworld, but Charon, the ferryman, doesn't like taking living people or people without a toll across.
Tartarus[]
Castle of Hades
Tartarus is the main part of the Underworld. Whenever Xena comes to the Underworld from Earth, she ends up in Tartarus first.
Tartarus is where the wicked go when they die. It's shown mostly like an endless dreary land of caves and tunnles with smoke and murky water everywhere. There is also random wreckage and lighting everywhere. The people in Tartarus just roam around helplessly forever, or are cocooned to a wall where they rewatch their lives over and over. Other parts of Tartarus have torture, fire, and lava pits.
Xena's personal Tartarus was a firey wasteland where she was crucified, and bubbles showing parts of her life were floating around. Callisto though said that compared to Hell, Tartarus was like the Elysian Fields.
Gate to the Elysian Fields
Hades' castle is in a part of Tartarus that is different that the rest of it. It has more space than the rest or Tartarus with it's own sky. It also has pits of lava and fire around it. In Tartarus there are entrances to the Elysian Fields. One is a doorway that leads straight to the paradise.
The Elysian Fields[]
The Elysian Fields
The Elysian Fields is a paradise where all the good people go when they die. In the Elysian Fields, everyone gets everything they could want, it's always Spring, there isn't any violence or pain, and everyone is happy. People also wake up every morning forgetting the day before, so they don't get lonely, and wait for their families to join them.
The Elysian Fields looks like a beautiful field with flowers that are always in bloom, springs and waterfalls, and tables of food and drinks.
When Xena rescued Solan from Tartarus, she took him to the Elysian Fields where he waits for her to join him.