One of the most dangerous breeds of jellyfish has been spotted in the sea near Sandycove in Dublin.
The Lions Mane has hundreds of tentacles capable of causing severe stings.
People are being warned to stay out of the water at Seapoint.
In a statement, Dún Laoghaire-Rathdown County Council said that warning signs have been erected in lifeguard patrolled areas at Seapoint as Lions Mane jellyfish have been spotted here and further into the bay.
They said, as an added precaution, the life guard warning flags are on red and will remain there till further notice.
Lifeguards are actively keeping a vigilant eye on the water and bathers.
Dún Laoghaire councillor Cormac Devlin, explained "Lions Mane jellyfish have particularly long hair-like tentacles which can cause a severe sting to bathers."
"I would urge swimmers to be cautious while swimming in Seapoint or around the coast this weekend," he added.
In 2014, seventeen of these venomous jelly fish were washed up at Sandycove and removed by Dún Laoghaire-Rathdown County Council.