Hell is the home and domain of the Demons within the Afterlife. It is also the place where all Medians go if they are considered 'evil' by Death. Although Hell itself is considered to be past Cerberus' gate, some may argue Hell begins with the River Styx and the Ring of the Slightly Damned.
Hell consists of three segments: Styx, The Ring of the Slightly Damned, and Hell itself. The Ring of the Slightly Damned consists of little more than dirt and rock, resembling a barren wasteland. Styx is a neon green river of an unknown liquid that somewhat resembles human faces. The gates to central Hell are massive black metal gates with a single padlock that only Cerberus can unlock. The inner parts of Hell are much more lively with lava streams, tormented souls, demons, and the occasional dead tree. According to Chu (citation needed), there are housing constructs somewhere within Hell, indicating that Demons do live in their own brand of civilization.
In a Q&A it's revealed that water does exist in Hell, mainly for the Water Demons to use for whatever torture they may have in mind for the more aquatic Medians (such as Khamega and Merfolk), and there's also frozen areas they can use as well. Water Demons also tend to use the water as a recreational area as well.
Demons are highly aggressive and sadistic. Most Demons seen in Hell tend to be occupied with torturing people and there doesn't seem to be much culture among the anarchy. Schools seem to exist, though they mostly involve learning about torturing Medians. Children, often orphans, are usually gathered up to be placed in training groups to become soldiers.
Not much is known about Hell other than it being of Syndel's creation and a central of sordid acts of torture upon the damned souls of the sinful.
After her brief stay in Purgatory, Rhea Snaketail was dropped off by Death in the Ring of The Slightly Damned with her Demon supervisor, Buwaro. While there isn't much to do in the ring Rhea and Buwaro were given the task to obtain a note Iratu had and give it to Sakido. This gave the two a chance to enter Hell. Rhea remained in the ring until she ascended with Buwaro and Sakido.