Holidaymakers are being warned to be extra vigilant as huge swarms of jellyfish have appeared on many of the UK's beaches, brought in by the warm weather.
Sightings of moon, compass, blue and lion's mane jellyfish have all been reported in recent days.
The lion's mane jellyfish has one of the most painful stings in British waters, after the Portguese Man of War, and has been spotted between the north Wales and Blackpool coast, reports the Daily Mail.
Experts are also warning holidaymakers to watch out for blue jellyfish as thousands have been spotted near the shore along the south west coast in recent weeks.
The Marine Conservation Society (MCS) is asking bathers to report their sightings of jellyfish by filling out a form on its website, explaining that they act as a good indicator of the state of the seas.
Dr Melanie Austen Head of Science at Plymouth Marine Laboratory, told the Daily Mail: "We think the rise is a result of warming waters due to climate change, which means there is more food around for the jellyfish.
"Overfishing may have also played a role, with a lack of larger fish that eat them and help keep numbers down."
"However, as our waters warmed, sightings of jellyfish increased, with moon jellyfish reported in large numbers around the UK, reports of compass and blue jellyfish in the South West, and blooms of lion's mane jellies around North Wales and north-west England."
There has only been one sighting of the deadly Portuguese Man of war this year (in Cornwall).
Back in September 2012, a woman was scarred for life after she was stung by jellyfish just hours after she arrived at a luxury resort in Thailand for a holiday.
Sam Webster, 37, suffered third degree burns and was left with horrific scarring after falling from a banana boat and being attacked by the dangerous animals.
Have you witnessed the invasion of the jellyfish in the UK? Tell us below!
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