Dangerous Portuguese man-of-war jellyfish have washed up on the coast in unprecedented numbers.
Scientists say exceptional numbers of the highly venomous jellyfish have been blown in from the open ocean by the recent strong Atlantic storms.
They deliver an excruciatingly painful sting which can be fatal in very rare cases, with beach-goers warned that even dead man-of-war jellyfish are still venomous.
Director of Dingle Oceanworld Kevin Flannery said they have been inundated with reports of the creatures in Kerry and Cork.
"The numbers are phenomenal. You are talking thousands. It's a serious issue. The place is littered with them in the south coast in the past week," he said.
"People are still surfing and windsurfing, and there is the odd swimmer. They could get a tentacle across the eye. The beaches are best avoided until they're gone."
He said he has around 60 of the creatures recovered alive in a tank in Dingle Oceanworld, which could be used for research purposes.
"I picked 14 or 15 in a 20-foot patch alone at the beach in Dunquin in Dingle.
"They are all over the place. There are huge numbers coming in, one woman reported 58 of them in one beach in Clonakilty.
"They are all the way up to Clare, all the way down the south coast, the south-west coast."
He said he had been in contact with local councils to put out warnings. "Don't touch them with a pitchfork. The burn is like boiling water being poured across you."
One local man said he was astonished to find so many of the venomous creatures in Kerry.
"I have been out on the ocean around Kerry for decades and I have never, ever seen anything like this.
"There is a real worry, children could pick them up mistaking them for plastic or harmless jellyfish."
Marine biologist Mr Flannery believes they were pushed up by recent Atlantic storms.
"They came straight up with the wind from the Azores and now with the south-westerly winds they are being pushed on to the beaches in the south of Ireland, the south-west of Ireland and in places like Cornwall," he said.
"They are like a sack of gas which gets pushed up with the weather."