Bathers have been warned to stay out of the water along part of Dublin’s coast as a dangerous breed of jellyfish returns to the bay.

Warning signs and red flags have been erected at Seapoint and areas of Sandycove following sightings of Lion’s Mane jellyfish in the water.

The largest known species of jellyfish, the Lion’s Mane boasts hundreds of lengthy tentacles capable of causing severe stings.

Local Fianna Fáil Councillor Cormac Devlin says changing tides and warmer weather are to blame for the increased sightings of the jellyfish in recent years:

“It is the type of thing itself that the hairline tentacles are so long that they obviously spread out throughout the water, he said.

“Unfortunately it is something that has plagued the coast for the last number of summers but I think the key thing here is to be aware of the presence of jellyfish.

“These particular ones - given the size of their tentacles - while they appear to be a long distance away; it is the tentacles that can actually cause the severe sting.”

Cllr Devlin said there were 17 of the jellyfish removed from the shoreline by the council last year.

Dún Laoghaire-Rathdown County Council said the lifeguard warning flags will remain on red until further notice, “as an added precaution.”

Lifeguards will be actively keeping a vigilant eye on the water and bathers.