Where Above names the destination reached by climbing the axis mundi, Below names the one reached by descending it, and the same vertical-axis cosmologies that give Above a sky realm generally give Below an underworld one. Yggdrasil's roots in Norse cosmology reach into Niflheim and other lower realms; the shaman's journey in Siberian and Central Asian traditions runs downward along the world axis to the lower spirits as often as it runs upward; and a great many mythologies place the land of the dead literally beneath the ground the living stand on, reached by a downward passage rather than an outward one.
Egyptian cosmology's Duat, the realm through which the sun travels each night and which the deceased must navigate to reach the afterlife, is one well-documented example of this pattern among many culturally distinct underworld traditions the direction can be read against.
Mesopotamian literature supplies one of the oldest surviving descriptions of the downward journey. The Sumerian account of Inanna's descent has the goddess pass through seven gates into the netherworld ruled by her sister Ereshkigal, surrendering an item of clothing or regalia at each gate until she arrives stripped, a structure that treats descent as progressive loss rather than as simple travel. Greek tradition names the same movement katabasis, a going down, and applies it to Odysseus at the edge of the underworld, to Orpheus and to Herakles, in each case as an exceptional passage a living person is not meant to make and does not make unchanged.