In Celtic mythology, the Otherworld is a mystical realm inhabited by deities, spirits, and heroes. It represents an alternate dimension where time flows differently and holds the afterlife for souls. The Otherworld is depicted as a place of eternal youth, beauty, and abundance, often accessed through various portals in nature, symbolizing a connection between realms. It encapsulates themes of transcendence and the mystical, serving as a refuge and a source of wisdom in Celtic tales.