Bundoran RNLI was launched after three swimmers got into difficulty at Tullan Strand on Friday evening.
The inshore lifeboat reached the scene shortly after 9.15pm, locating one casualty who had made it onto rocks.
The other two swimmers reached shore, with one assisted by a surf instructor from Bundoran Surf Club. One swimmer was airlifted to hospital by Rescue 118 for further treatment.
Bundoran Fire Brigade, the National Ambulance Service and An Garda Síochána also assisted.
The crew launched again yesterday following reports of a casualty in the water, but after an extensive search the call was stood down and deemed to have been made in good faith.
