Dublin beachgoers have been warned to be on guard for a particularly venomous jellyfish.
A sign has been posted at Dollymount Strand warning that Lions Mane jellyfish are present in the water.
Dublin City Council said jellyfish often make regular appearances in our seas.
A spokesperson said: "Jellyfish are a seasonal problem and regularly appear in Dublin Bay.
"The sign was put up three to four weeks ago and is a precautionary measure advising people that jellyfish may be present in the water. Similar signs have been put up before."
Although the Lions Mane breed -- which has one of the most venomous stings -- is mostly prevalent in Dublin Bay, other beachgoers have reported sightings in Rush, Malahide and Co Louth.
They traditionally emerge in May and disappear in September, when temperatures cool down again. A Facebook page has even been established by Irish jellyfish fanatics -- eager to learn more about the sudden influx of the creatures.
The Big Jellyfish Hunt page encourages beachgoers to report any sightings they might have of the creatures and speak about their particular experiences.
Swimmers who have been stung by the fish said that they didn't see anything but what looked like 'seaweed' in the water.