In Celtic mythology, Mag Mell ("plain of joy") is a paradise where the deceased live. In contrast with other realms of the dead, Mag Mell is described as an idyllic island, or as a wonderful place at the bottom of the ocean. This realm of the dead is ruled by king Tethra of the Fomorians, a race of giants. But also the sea god Manannan mac Lir of the Tuatha Dé Danann is believed to rule there. Another name for this place is Tir na n-Og ("land of youth").