Dún Laoghaire/Rathdown County Council has erected signs at four of the most popular swimming areas in south Dublin because of the presence of dangerous jellyfish in the water.
The council is advising people to stay out of the water and has erected signs to that effect at Seapoint, Sandycove, the Forty Foot and Killiney beach.
Three people were treated in St Michael's Hospital in Dún Laoghaire yesterday for jellyfish stings.
