Lough Gur is today much different than it was in prehistory. Now resembling the open mouth of a dragon, the lake once formed a complete circle, with the present-day Hill of Knockadoon a large island on its eastern side. Drainage schemes in the 1840s resulted in the shape of the lake seen today. The water level was lowered by about 2.4 meters (8 ft) exposing much in the way of archeological treasures, such as the presumed votive offering of a small sword. The lake today is a placid wildlife sanctuary where no motorized watercraft are permitted. The Interpretative Center, located in a reproduction of a Neolithic hut, offers displays and an audiovisual overview of the area.

Many of the stories of the enchanted Lough Gur center on the life and legends of Gerald, or Garrett, Fitzgerald, the third Earl of Desmond, the scion of the Munster branch of the Hiberno-Norman Geraldines. He died (some say he disappeared) in 1398. The island near the east shore of Lough Gur, Garrett Island, is named after him. He is known locally as Geároid Iarla, or Earl Gerald, in legend the son of the goddess Áine from nearby Knock Áine. From his mother he gained his powers of sorcery. Geároid lives there in the under-lake world to this day, awaiting the time of his normal return to the world of men. But once in every seven years, on clear moonlight nights, he emerges temporarily, when the Lough Gur locals would see him as a phantom mounted on a phantom white horse, leading a phantom or fairy cavalcade across the lake and land.