The elderly couple that sadly passed away yesterday while snorkelling on the Barrier were apparently stung by Irukandji. Authorities believe this resulted in at least one them having cardiac issues and tragically drowning.
The worst we get down our way are blue bottles, and they are a big enough pain. I am kind of happy that I have a pool at home and at my inlaws around the corner, though you still need to be wary of the occasional funnel web in the water and for some reason German and Dutch backpackers.