Be careful if you’re swimming in the sea during this lovely weather, because there could be something lurking in the water.

People enjoying their first dip of the season may encounter unexpected visitors- as Barrel jellyfish, normally only seen off the southeast coast, have been washing up in large numbers from Lough Foyle down to west Cork.

UCC scientist Dr Tom Doyle told the Irish Times Barrel jellyfish, named because they can weigh 25 kilos, look scary but don’t really sting.

“Normally, we would only hear of them off Rosslare in Co. Wexford where there can be several thousand barrel jellyfish,”

“Up to now, they have tended to be found in certain coastal pockets on these islands, like Carmarthen Bay in Wales.”