In Celtic mythology, the Otherworld is the realm of the deities and possibly also the dead. In Gaelic and Brittonic myth it is usually a supernatural realm of everlasting youth, beauty, health, abundance and joy. It is described either as a parallel world that exists alongside our own, or as a heavenly land beyond the sea or under the earth. The Otherworld is usually elusive, but various mythical heroes visit it either through chance or after being invited by one of its residents. They often reach it by entering ancient burial mounds or caves, or by going under water or across the western sea. Sometimes, they suddenly find themselves in the Otherworld with the appearance of a magic mist, supernatural beings or unusual animals. An otherworldly woman may invite the hero into the Otherworld by offering an apple or a silver apple branch, or a ball of thread to follow as it unwinds. The Otherworld is usually called Annwn in Welsh mythology and Avalon in Arthurian legend. In Irish mythology it has several names, including Tír na nÓg, Mag Mell and Emain Ablach. In Irish myth there is also Tech Duinn, where the souls of the dead gather. Irish mythology In Irish mythology, the Otherworld has various names. Names of the Otherworld, or places within it, include Tír nAill ("the other land"), Tír Tairngire ("land of promise/promised land"), Tír na nÓg ("land of the young/land of youth"), Tír fo Thuinn ("land under the wave"), Tír na mBeo ("land of the living"), Mag Mell ("plain of delight"), Mag Findargat ("the white-silver plain"), Mag Argatnél ("the silver-cloud plain"), Mag Ildathach ("the multicoloured plain"), Mag Cíuin ("the gentle plain"), and Emain Ablach (possibly "isle of apples"). It is described as a supernatural realm where there is everlasting youth, beauty, health, abundance and joy, and where time moves differently. It is the dwelling place of the gods (the Tuatha Dé Danann) as well as certain heroes and ancestors. It was probably similar to the Elysium of Greek mythology and both may have a shared origin in ancient Proto-Indo-European religion. The Otherworld is elusive, but various mythical heroes—such as Cúchulainn, Fionn and Bran—visit it either through chance or after being invited by one of its residents. In Irish myth and later folklore, the festivals of Samhain and Beltane are liminal times, when contact with the Otherworld was more likely. In the tales, the Otherworld is