Garda say a woman sustained serious injuries in Bundoran at the weekend.
The incident occurred near Tullan Strand in the early hours of Saturday morning after the woman fell 40foot from a cliff while the Sea Sessions festival was underway.
The woman, who is in her early twenties sustained serious injuries to her leg.
She is being treated in hospital in Dublin where she is said to be in a stable condition.
Gardai say there was also a large number of drug detections at the three day festival.