Red warning flags are flying over four popular south Dublin beaches warning swimmers not to go into to water due to the presence of dangerous, stinging jellyfish.
Three people needed hospital treatment yesterday after being stung.
A spokesman for Dún Laoghaire/Rathdown Co Council said red flags were flying at the council's lifeguard beaches at Seapoint, Killiney, Sandycove and the 40 Foot.