, a modern attempt to reconstruct the Norse world tree which connects the heavens, the world, and the underworld.
The legs of the god
as the Cosmic Man depict earth and the seven realms of the Hindu underworld of
. The feet rest on cosmic serpent
underworld is the supernatural world of the dead in various religious traditions and myths, located below the world of the living.  Chthonic is the technical adjective for things of the underworld.
The concept of an underworld is found in almost every civilization and "may be as old as humanity itself".
Common features of underworld  myths are accounts of living people making journeys to the underworld, often for some heroic purpose. Other myths reinforce traditions that entrance of souls to the underworld requires a proper observation of ceremony, such as the ancient Greek story of the recently dead Patroclus haunting Achilles until his body could be properly buried for this purpose. Persons having social status were dressed and equipped in order to better navigate the underworld. 
A number of mythologies incorporate the concept of the soul of the deceased making its own journey to the underworld, with the dead needing to be taken across a defining obstacle such as a lake or a river to reach this destination.
Imagery of such journeys can be found in both ancient and modern art. The descent to the underworld has been described as "the single most important myth for Modernist authors". 
This list includes underworlds in various religious traditions, with links to corresponding articles.
Naraka (also Niraya)
Annwn, Mag Mell, Dubnos
Chinese folk religion / Taoism
Hell, Tártaro, Purgatory
Aaru, Duat, Neter-khertet, Amenti
Burotu, Murimuria 
Elysium, Asphodel Meadows, Tártaros
Patala, Naraka or Yamaloka
Dankuš daganzipaš/Dankuš tekan (dark earth)
Naraka, Adho Loka (the lower world)
Japanese mythology/ Shinto
Yomi 黄泉, Ne-no-Kuni 根の国, Jigoku 地獄
Sheol, Gehenna, Abaddon, Tehom (in Kabbalah), Tophet, Tzoah Rotachat, Dudael
"Ji-Ok" 지옥 地獄
Alam Ghaib (The unseen realm)
Hawaiki, Rarohenga, Rangi Tuarea, Te Toi-o-nga-Ranga, Uranga-o-Te-Ra
Pellumawida, Degin, Wenuleufu, Ngullchenmaiwe
Bulu, Burotu, Murimuria, Nabagatai, Tuma
Gimlé, Hel, Niflhel, Vingólf
Avaiki, Bulotu, Iva, Lua-o-Milu, Nga- Atua, Pulotu, Rangi Tuarea, Te Toi-o-nga-Ranga, Uranga-o-Te-Ra
Nav, Podsvetie, Peklo, Vyraj
Wagawaga (New Guinea) mythology
This list includes rulers or guardians of the underworld in various religious traditions, with links to corresponding articles.
Baiame ( Kamilaroi), Eingana
Allu, Anu, Anunnaku, Ereshkigal, Etemmu, Gallu, Humbaba, Mamitu, Nergal, Utnapishtim
E Bukura e Dheut
Mictlantecuhtli, Mictecacihuatl, Chalmecacihuilt, Chalmecatl
Erra, Nergal, Ninlil, Sursunabu, Ur-shanabi, Utnapishtim
Batara Kala, Setesuyara
Aed, Arawn, Cwn Annwn, Donn, Gwyn ap Nudd, Manannán mac Lir, Pwyll
Chinese folk religion
Yanluo Wang, Heibai Wuchang
Satan, Lucifer, Beelzebub
Aken, Aker (strictly only the gatekeeper), Am-heh, Amunet, Ammit, Andjety, Anubis, Apep, Apis, Astennu, Ha, Imiut (if the Imiut was ever considered a god), Isis, Mehen, Naunet, Nehebkau, Nephthys, Nun, Nut, Osiris, Ptah, Seker, Thoth
Charun, Culsu, Februus, Mania, Mantus, Nethuns, Tuchulcha, Vanth
Kalma, Kipu-Tyttö, Kivutar, Lovitar, Surma, Tuonen akka, Tuonetar, Tuoni, Vammatar
Cerberus, Charon, Hades, Pluto, Keres, Persephone, Thánatos
Hattian mythology, Hittite mythology
Indonesian mythology (ancient Javananese, Sundanese and Balinese)
Batara Kala guardian for sinners souls' underworld, Dewi Sri guardess for the righteous souls' underworld
Izanami-no-Mikoto, Jikininki, Shikome, Shiryō, Susanoo-no-Mikoto
Satan, Malach HaMavet("Angel of Death") (both are associated with
Samael), Malachei Habala ("Sabotage Angels")
Veļi, Veļu māte, Zemes māte
Hina, Hine-nui-te-Po, Kewa, Mahiuki, Rohe, Whiro
Hun-Came, Vucub-Came, Kisin
(includes Fijian mythology)
Degei, Ratumaibulu, Samulayo
Garmr, Hel, Ran, Nidhogg
Angra Mainyu, Azhi Dahaka, Peri
Hikuleo, Hina, Hine-nui-te-Po, Kanaloa, Kiho-tumu, Makea Tutara, Mahiuki, Mahu-ike, Marama, Mauri, Merau, Milu, Miru, Rimu, Rohe, Whiro
Roma (Gypsy) mythology
Cerberus, Dea Tacita, Dis Pater, Egestes, Fames, Inferi Dii, Larenta, Letum, Libitina, Mors, Orcus, Pluto, Proserpina, Viduus
Diavolu, Satana, Necuratu, Scaraoschi
Crnobog, Flins, Marzana, Nyia, Veles (god)
Edimmu, Ekimmu, Endukugga, Enmesarra, Ereshkigal, Gidim, Gula, Irkalla, Kur, Namtar, Nergal, Neti, Nindukugga, Ninlil, Urshanabi, Ziusudra
Baron Cimetière, Baron La Croix, Baron Samedi, Ghede, Maman Brigitte, Marassa Jumeaux
Annwfn or Annwn
"Underworld". The free dictionary . Retrieved . 1 July 2010
Isabelle Loring Wallace, Jennie Hirsh,
Contemporary Art and Classical Myth (2011), p. 295.
Radcliffe G. Edmonds, III,
Myths of the Underworld Journey: Plato, Aristophanes, and the 'Orphic' Gold Tablets (2004), p. 9.
Underworlds: Philosophies of the Unconscious from Psychoanalysis to Metaphysics (2014), p. 1.
Evans Lansing Smith,
The Descent to the Underworld in Literature, Painting, and Film, 1895-1950 (2001), p. 257.
Evans Lansing Smith,
The Descent to the Underworld in Literature, Painting, and Film, 1895-1950 (2001), p. 7.
T. Williams, J. Calvert,
Fiji and the Fijians, Heylin, 1858.