Percy Jackson and the Olympians: Legends

Tartarus is a place of pain and suffering for gods and mortals, among others, designed to hurt them, with acid air, water of sadness (in the case of the River Cocytus) and the ground made of broken glass. Tartarus has a grayish atmosphere and its clouds are blood red. The ceiling is so high that it is invisible from the ground, stretching for miles and miles to plunge into darkness in the form of plateaus. Multiple pointed mountains and volcanic chasm adorn the landscape. A few long, thin, black trees (like insect hair) grow in the flatter areas, and multiple monsters emerge like worms from blisters that form on the ground where they regenerate after having been killed. The main wall of the cave is made up of multiple precipices and obsidian cliffs, where the rivers of Hades descend, presumably in the form of waterfalls, although this is not mentioned. The landscape descends to the most dangerous area, where the heart of the god himself is found.