5 Rivers of Hades; and Hypnos Cave, Greek Mythology

The Five Rivers of Hades

Leethe/Lethe, the river of "oblivion", is one of the five rivers in Hades, the Underworld ruled by Hades.  Leethe in ancient Greek means "a concealed thing" or "a forgotten thing". A-leetheia in Greek means "truth", or, "A" (without), being concealed or forgotten.  The river flowed around and through the cave at Hypnos. 

(YYpnos = personification of sleep [in Roman Mythology "Somnus"]. Hypnos' twin brother is Thanatos ("death"); and their mother in common (half brothers by maternity) is Neex ("night"). Hypnos has three brothers that represent what occurs in sleep, Morpheus/"shapener" [takes human forms in dreams], Phobetor/"frightening" [appears in dreams as darkness, animals, and monsters, the ruler of nightmares], and Phantasos/"apparition" [appears in dreams as inanimate objects]). 

Those whom drank the waters of Leethe were thrown into a memory loss or into a state of forgetfulness.  The sun never shines in Hypnos' cave, and their are some hallucinogenic plants, like poppy flowers, at its entrance.  

Styx/Steex, the river of hatred, is a prominent one, and one of the five rivers of Hades.  Styx is the border line between the living on Earth and the deceased souls whom have morphed back into their human forms to Hades.  During the War of the Titans, the Goddess Styx defended Zeus, and so Zeus later declared all oaths must be sworn upon her.  The major rivers in Hades also converge on a large marshy land, also called "Styx".  Styx is the Goddess of the River Styx.  Achilles was dipped into the river by his mother when he was young, and became invulnerable, except in the spot where his mother held him while dipping him into the river-his heel.  

Acheron/AxEron is the river of pain.  Charon ("xAron"), the ferryman of Hades that would ferry the souls of humans recently deceased to Hades, would cross not only the Styx, but also have to ferry across the axEron to get the souls to Hades (to pay for xAron's fee, a coin was commonly placed in the mouths of the deceased).  It has been described as both a place of punishment, as well as, a place for purging humans of their sins.  

Phlegethon, pyriphlegethon/fleyEthon, peereefleyEthon, is the river of fire.  It runs parallel to the river Styx and is a stream of fire that coils around the Earth.  The Goddess Styx fell in love with the God Phlegthon, but becoming consumed by his flames, she was sent to Hades.  Once in Hades with her river Styx, they reunited their love once again, Styx running parallel to Phlegethon.  

Cocytus or Kokytos (KokeetOs) is the River of "lamentation" or wailing.  It flows into Acheron which of course is a boundary river to Hades.