Thousands of people were stung by highly venomous jellyfish in north-eastern Australia over the weekend, forcing authorities to close several beaches.
Since the start of December, there have been more than 18,000 stings recorded in Queensland, compared with 6,000 for the same time previous year.
Coastguard association Surf Life Saving said a "whopping" 3,595 people had suffered painful burns after encounters with the creatures, also known as bluebottles for their transparent bluish appearance.
Across Queensland, but mostly in the southeast, 22,282 people sought treatment for bluebottle stings between December 1 and January 7, compared to 6831 in the same period a year ago.
"Those figures, the 22,282, are for about five weeks and that's just one teeny tiny smidgen of Australia, so that is a lot".
Most of those stung were on the Gold Coast, while there were also many stung on the Sunshine Coast.
They are most prevalent in sub-tropical regions but sometimes turn up en masse in North Queensland.
Bluebottle jellyfish colonies appear like blue-tinged sacs which measure up to 15cm (6 inches) long.
Lifesavers described the jellyfish on one beach as being like "a wall", and wrote on Twitter that the invasion was due to northeasterly winds.
AMSAS director Lisa Gershwin said it was "shaping up to be a pretty bad year".
"Some of the bluebottle sails are right-handed and some are left-handed, across the body, so when the wind comes up it only grabs the ones with the sail going the right way for that particular breeze".
The stings are typically mild and can be treated with ice or hot water, however some people had required treatment by paramedics at the weekend, Surf Life Saving Queensland (SLSQ) said.