Irukandji syndrome is a painful, potentially lethal condition caused by certain jellyfish from the Cubozoa class (box jellyfish) species. Although the sting is usually mild, systemic symptoms resembling a catecholamine surge can result in approximately half an hour, including tachycardia, hypertension, severe pain, muscle cramping, and is often followed by hypotension, pulmonary edema, and potentially life-threatening cardiac complications.[1]
— Read on www.ncbi.nlm.nih.gov/books/NBK562264/
Prehospital and Retrieval Medicine – THE PHARM dedicated to the memory of Dr John Hinds
In memory of Dr John Hinds
Prehospital and Retrieval Medicine - THE PHARM dedicated to the memory of Dr John Hinds 
The stings and resultant Irukandji syndrome are serious enough to require urgent tests and lifesaving treatment nearby. But it becomes guesswork in predicting the tiny Cubozoa class of jellyfish’ next appearance and seemingly random stinging events at random beaches.
Someone needs to invent something which could repel them without inflicting damage to the environment.
Or perhaps better would be discovering a way to reveal the swarms, testing various spectrums; using drones capable of sighting the nearly invisible jellyfish swarms; setting up alarms so that on first sighting, local authorities would be notified, and could shut down affected beaches, preventing serious injuries to tourists and locals, and increasing tourist dollars.
Wondering if climate change has increased the numbers of the Cubozoa jellyfish whose stings are responsible for Irukandji syndrome.
Or perhaps climate change may have negatively impacted the numbers of predators which might otherwise consume Cubuzoa jellyfish.