In Celtic mythology, the Otherworld is a place where gods and possibly the dead live. In Gaelic and Brittonic myths, it is often described as a magical land filled with eternal youth, beauty, health, plenty, and happiness. This realm is sometimes seen as a world that exists next to ours, or as a distant land beyond the sea or beneath the earth. The Otherworld is hard to find, but many heroes in myths visit it by chance or after being invited by someone who lives there. They may enter it by going into ancient burial mounds, caves, under water, or across the western sea. At times, heroes suddenly appear in the Otherworld after seeing a magical mist, strange creatures, or unusual animals. A woman from the Otherworld might invite a hero by giving him an apple, a silver apple branch, or a ball of thread to follow as it unwinds.
The Otherworld is called Annwn in Welsh mythology and Avalon in Arthurian legends. In Irish mythology, it is known as Tír na nÓg. Other names for this place include Mag Mell, Emain Ablach, and Tech Duinn. Tech Duinn is where the souls of the dead are believed to gather.
Irish mythology
In Irish mythology, the Otherworld has many names. Some names include Tír nAill ("the other land"), Tír Tairngire ("land of promise"), Tír na nÓg ("land of youth"), Tír fo Thuinn ("land under the wave"), Tír na mBeo ("land of the living"), Mag Mell ("plain of delight"), Mag Findargat ("white-silver plain"), Mag Argatnél ("silver-cloud plain"), Mag Ildathach ("multicoloured plain"), Mag Cíuin ("gentle plain"), and Emain Ablach (possibly "isle of apples").
The Otherworld is a supernatural place where youth, beauty, health, abundance, and joy never end. Time moves differently there. It is where gods, such as the Tuatha Dé Danann, and some heroes and ancestors live. This realm may have similarities to Elysium in Greek mythology, and both might have roots in ancient Proto-Indo-European religion. The Otherworld is hard to reach, but some heroes, like Cúchulainn, Fionn, and Bran, visit it by chance or after being invited by someone from there. In Irish myths and later stories, the festivals of Samhain and Beltane are times when the boundary between the world and the Otherworld is thinner, making contact more likely.
The Otherworld is often entered through ancient burial mounds, such as those at Brú na Bóinne and Cnoc Meadha. These mounds were called sídhe ("Otherworld dwellings") and were homes to the gods, later known as the aos sí or daoine sí ("Otherworld folk"). According to Irish myths, the gods moved into the sídhe after the Gaels (Milesians) took over Ireland. In some stories, the Otherworld is reached by going under water or crossing the western sea. In tales called "Immrama" ("voyages"), a young woman from the Otherworld often approaches a hero, sings about her homeland, and offers an apple or her love in exchange for help in battle. The hero follows her, and they travel together across the sea, disappearing forever. Their journey might take place in a glass boat, a chariot, or on horseback, often a white horse, like the goddess Niamh of the Golden Hair.
Sometimes, the hero returns after what seems like a short time, only to find that years have passed and his friends are dead. Other times, the hero goes on a quest and is surrounded by a magic mist. He may arrive at a strange palace and meet a warrior or a beautiful woman, such as the goddess Fand or the warrior Manannán mac Lir or Lugh. After unusual adventures, the hero may return successfully. However, even if the hero returns to his world, he is forever changed by his time in the Otherworld.
The Otherworld was also a place of authority. In the tale Baile in Scáil ("the phantom's ecstatic vision"), Conn of the Hundred Battles visits an Otherworld hall where the god Lugh confirms his kingship and that of his descendants.
In Irish myths, there is another realm called Tech Duinn ("House of Donn" or "House of the Dark One"). It was believed that the souls of the dead traveled to Tech Duinn, possibly staying there forever, or before reaching their final destination in the Otherworld, or before being reborn. Donn is seen as a god of the dead and an ancestor of the Gaels. Tech Duinn is often linked to Bull Rock, an island off Ireland’s west coast that looks like a portal tomb. In Ireland, it was believed that souls of the dead traveled westward over the sea with the sunset. This direction was also thought to be where the phantom island called Hy-Brasil was located.
Welsh mythology
In Welsh mythology, the Otherworld is often called Annwn or Annwfn. The Welsh story of Branwen, daughter of Llyr, ends with the survivors of a great battle celebrating in the Otherworld. They are in the presence of the severed head of Bran the Blessed. They have forgotten their pain and sadness and no longer notice the passing of time. Annwn is ruled by the Otherworld kings Arawn and Gwyn ap Nudd.
In the First Branch of the Welsh tales called the Mabinogi, titled Pwyll, Prince of Dyfed, the prince named Pwyll offends Arawn, ruler of Annwn, by teasing his hunting hounds on a stag that Arawn's dogs had already brought down. To make up for this, Pwyll agrees to swap places with Arawn for one year. During this time, Pwyll defeats Arawn's enemy, Hafgan. Meanwhile, Arawn rules Dyfed. While in Annwn, Pwyll does not sleep with Arawn's wife, which earns him Arawn's appreciation. When Pwyll returns, he is given the title Pen Annwn, meaning "Head (or Ruler) of Annwn."
Continental Celtic mythology
The Gauls divided the universe into three parts: Albios ("heaven, white-world, upper-world"), Bitu ("world of the living beings"), and Dubnos ("hell, lower-world, black-world"). Lucan wrote that Gaulish druids believed the soul went to an Otherworld, which he called by the Latin name Orbis alius, before being reincarnated.
Greco-Roman geographers recorded that the Celts believed in islands sacred to gods and heroes. These included Anglesey (Môn), off the north coast of Wales, which was the sacred isle of the druids of Britain; the Scilly Isles, where remains of early temples have been found; and some of the Hebrides, which in Gaelic tradition were home to ghosts and demons. On one of these islands, Skye, the Irish hero Cúchulainn was taught by the warrior woman Scathach.
Byzantine scholar Procopius of Caesarea described the Otherworld of the ancient Gauls. He wrote that people believed the land of the dead was located west of Great Britain. Continental Celtic myths said that after leaving their bodies, souls traveled to the northwest coast of Gaul and took a boat toward Britain. When they crossed the Channel, the souls went to the homes of fishermen and knocked desperately at their doors. The fishermen then led the souls to their destination in ghostly ships.
Beliefs about the Otherworld still appear in the folklore of Brittany. There, the name Bag an Noz is used to refer to ships that carry the dead to their goal. Anatole Le Braz described in his book La légende de la mort chez les Bretons armoricains the existence of soul processions that travel to coastal places like Laoual to begin their final journey.
In Asturian mythology, many stories describe human encounters with xanas, fairies who dance around a chief fairy, the Xana Mega, or the "Queen of Fairies," known as xacias in Galicia. The castro of Altamira is said to hide an enormous underground realm ruled by a royal couple, with an entrance located somewhere on the hill.
Modern treatments
Modern writers like J. R. R. Tolkien, C. S. Lewis, Jim Butcher, and George R. R. Martin have taken ideas from the Celtic Otherworld, a magical place in Celtic traditions. In Tolkien's The Hobbit, the story enters a magical forest called Mirkwood, which is inspired by the Otherworld. In Lewis's The Chronicles of Narnia, a magical land named Narnia is home to talking animals, magical creatures, and other supernatural beings. In Butcher's The Dresden Files, supernatural characters come from a different world called the "Nevernever," including beings like the Sidhe (based on the Aos Sí) and the Tuatha Dé Danann. In Martin's A Song of Ice and Fire, magical groups such as the Children of the Forest, Giants, and the Others are linked to a place called the Lands of Always Winter. The Others are specifically described as "Sidhe made of ice."