Aussie surfer here, the stings typically are uncomfortable. Some of the deadlier ones can be close to painless and only result in itching and result in you dying from respiratory failure 24 hours later. Others are downright painful with even strong opiate based pain killers struggling to cut through the pain.
Also it's in a way normalised to happen in a few places with beaches. There are vinegar stations every 100m or so. Basically a "yes, it will happen to a few of you".
Townsville's Strand has a number of them for example. (Really bad lighting, but I believe it's that green board: https://maps.app.goo.gl/x7gggCjGwxVqDBx79?g_st=ac) I went down the Qld coast a couple of weeks ago and they're still very common.
Is the deadly itchy one of those tiny box jellyfish? More than sharks or crocs, this is why I was an absolute coward and decided not to get in the water in Queensland. There are lots of ways to die, but I'd prefer not to blame myself in my last moments.
