A mum said she was left feeling "stung all over" after swimming in the sea on a family trip to the beach.
Diana Scott, 41, went for a dip with her husband and two daughters when they got struck by - what they described as - an intense nettle sting.
The family had been spending the day at North Bay in Scarborough, Yorkshire, after recently moving to the area.
But what was meant to be a refreshing swim turned into a medical scare after Diana was left with a serious tingling sensation all over her body, which seemed to come and go.
"We moved to Scarborough nine weeks ago and every day I have gone down to swim at north bay I've had a tingling sensation," she told Yorkshire Live.
"But the other day it was really quite bad. Both my girls have surf suits and only on their legs and arms they could feel it.
"My partner, who doesn't go into the water, had it all over his legs.
"It felt like a really intense nettle sting. It's there then disappears and comes back again, it's really weird.
"There is no rash or anything just the sensation, it was really strange."
Diana shared her concerns on Facebook where others speculated that jellyfish could be behind the mystery sting.
Echoing their sentiments, Diana recalled seeing jellyfish in the sea after the incident while strolling along the beach with her children.
She said: "Obviously when they are little, you cant see anything. We couldn't see any when we were swimming.
"Its kind of put me off going in. I'll have to buy a wet suit."
Swathes of stinging jellyfish are appearing along the UK coast as temperatures rise throughout the summer.
The often beautiful sea creatures have washed up on Welsh beaches, from the Irish Sea, and on English beaches, from the North Sea.
Holidaymakers hoping to cool down in the sea have been warned to heed caution as recent heatwaves have brought the blubbery creatures closer to shore.
While jellyfish are generally not dangerous in the UK, their sting can pack a punch and encountering one could be painful.
Amy German, jellyfish supervisor at Scarborough Sea Life Centre, said that it's not unusual to see more jellyfish blooms when the weather warms up.
She explained that there could be several reasons for the increase in numbers but that it is mostly temperature-related.
"The jellyfish breed in the summer months when the water warms up and plankton is more abundant for babies to eat," she said.
"So that's why they choose the summer months to breed.
"If it's a particularly good year you'll end up with larger blooms of jellyfish, so it could be that we're having a good year for certain species of jellyfish and so there's more in the sea.
"They're influenced by the ocean currents, so if the sea washes them towards the beaches then that's where they'll go."
Amy said that it is common to see many jellyfish in one place at one time because they are moved around by the sea currents.
"They'll tend to all get washed up at the same time because that's the way that the direction of the sea is taking them at that particular time of day," she added.
Entering the sea can therefore come with the risk of being stung, with some species packing a more painful punch than others.
Amy added: "Some species you wouldn't even notice if they brushed up against you, like moon jellyfish. They're quite distinctive and are harmless, their sting isn't really strong enough to sting through the skin.
"Compass jellyfish – the ones with long, trailing hair-like tentacles – lion's mane, and blue jellyfish are the key players of the stinging jellyfish.
"It's hard to avoid them other than not getting in the sea. If you are going to get stung it's usually because they just waft over and their tentacles are so long and hair-like that they brush against you."
