The public have been advised not to bathe in the Sandycove area of south Dublin due to the presence of a dangerous jellyfish in the water there.
The Lions Mane jellyfish has been spotted in the water at Seapoint and further out in Dublin Bay.
A statement on the Dún Laoghaire-Rathdown County Council website says that warning signs have been erected in affected areas.
In addition, lifeguard warning flags are on red and will remain so until further notice. Lifeguards are also on duty in the area.
The Lions Mane jellyfish is one of the most dangerous jellyfish in Irish waters.
They can grow up to two metres wide and have hundreds of tentacles capable of causing severe stings.
Earlier this week, Irish Water Safety issued a warning about Lions Mane jellyfish around the Ard an Rátha area of Co Donegal.
The jellyfish are usually more commonly found on Ireland's east coast.