A free diver has said he "couldn't believe his luck" after spotting a giant jellyfish off the Welsh coastline.
Iestyn Morgan, from Pembrokeshire, said the lion's mane was the "length of a bus" with a size of about 10 to 15 metres (32ft 8in to 49ft 2in).
The 21-year-old conservationist, who records footage for social media to raise awareness about the "threats our seas are facing", said it was the first lion's mane he had seen in Wales.
More commonly found in the colder waters off Scotland, a marine biologist said although the lion's mane sting was "nasty", it was not dangerous.
Morgan said he was swimming near Trefin Beach in Pembrokeshire when he spotted the tentacles in the water.
The jellyfish was so big the tentacles went "beyond the range of visibility".
The Wildlife Trusts, external said the lion's mane jellyfish gets its name from its long tentacles, and has "all the beauty and bite of a lion".
Marine biologist Dr Cathy Lucas, from the University of Southampton, said Morgan's video showed the animal's length.
"The tentacles are so long and so fine you might not even see them," she said, recalling how during field work in Scotland divers would get bits of tentacles on them when there were no jellyfish around.
Lucas said lion's manes "occasionally" reach the Welsh coast later in the summer or autumn, according to jellyfish sightings recorded by the public, but their main habitat in the UK was Scotland.