Tartarus is the place in Hades reserved for the vilest individuals, separating itself from the rest of the Underworld by means of the fiery Phlegethon. Those sent to Tartarus are placed under the watch of the Erinyes. There they are tasked to eternal torment, never receiving satisfaction or pleasure despite any efforts. The best examples of some of the tortures given are Sisyphus’s impossible task to move a large boulder and Tantalus’s insatiable thirst in the receding waters. It is said that the Cocytus was formed from the salty tears of those unfortunate enough to get sent to Tartarus.
Elysium, on the other hand, is the exact opposite. It is where those of innocent hearts and righteous actions rest in bliss. It is more like the living world than any other region in Hades, with lush forests and a variety of fragrant flowers. Passing through the Elysian fields is the river Lethe, designed to erase the memories of anyone who drinks from it. Many of the heroes in Greek and Latin mythology end up in Elysium, existing peacefully with their loved ones and enjoying their afterlives.
Beyond both Elysium and Tartarus lies the Cave of Sleep, where Somnus, god of sleep, and Mors, god of death, reside. Watching over them was Morpheus, minister of Sleep and Keeper of Dreams. The cave itself is dark and quiet, with poppies scattered along the grounds.
Source: Guerber, Helen. Classical Mythology. Fall River Press, 2018, ppg. 2, 160-170, 211.
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