Mashable: We don't want to cause a national panic or anything, but it seems that more and more horrendously large jellyfish are setting up shop in UK waters.
See also: Seriously unexpected marine mammals are being spotted in the River Thames
According to reports from the Marine Conservation Charity (MCS), record numbers of "massive" barrel jellyfish, which can grow up to 1 metre wide and weigh 25 kg, have shown up over the last year. And there's also the scary Portuguese man o' war that have been seen...