No fatalities have been confirmed and for most people the stings are harmless - albeit painful - but they can cause problems for those with allergies, as well as the young and the elderly.
Thousands of people were stung by highly venomous jellyfish in north-eastern Australia over the weekend, forcing authorities to close several beaches.
Surf Life Saving Queensland said over 2,600 people received treatment at the weekend. More than 18,000 stings were recorded in Queensland in December, three times more cases than previous year over the same period.
Bluebottle jellyfish colonies appear like blue-tinged sacs which measure up to 15cm (6 inches) long. Stings can be painful but are typically not risky, though some people can be allergic. The number of those cases was not recorded.
A statement from Surf Life Saving Queensland said that due to the northeasterly winds, we will continue to see bluebottles hanging around.
The jellyfish activity forced the closure of busy beaches.
Bluebottle jellyfish washed up on Sidmouth beach in Devon, England in this illustrative image.
Bluebottles, sometimes known as the Indo-Pacific man-of-war, are a common sight at Australian beaches in summer and are often blown ashore or into shallow waters.
But a SLSQ spokesman described the latest influx as an "epidemic", while some local media outlets labelled it an "invasion". "So, it's reasonable to say that the jellyfish might potentially be responding to the warmer-than-usual weather", said marine life researcher Lisa Gershwin, who works with the Commonwealth Scientific and Industrial Research Organisation, which is Australia's national science agency.
However, the number seen in Queensland during the weekend is particularly unusual.