The "No Swimming" thing is just a bit of trivia that Tally Ho (cigarette paper manufacturer) includes inside each booklet. Your perception was a little "skewed" methinks? Perhaps chemically enhanced??
Bush Scorpion stings can be painful, but not fatal, much like a Bull-Ant bite (imagine an ant about 2 inches long with large pincers & very aggressive). I've been bitten on the ball-sack by a few of them when I made the mistake of sitting down on a nest. A real borderline thrill, I can tell you!!
It's the other bastards you have to be wary-of. Where I live, it's Tigers at this time of year. NO, I don't mean big pussy-cats with 4 legs & a tail, but Tiger Snakes. This is a small one (about 1m long) I snapped around my shed a few years ago:
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I went out to tend my bush grow plot a couple of weeks ago & almost stepped on one twice that size.
A small one killed my favourite dog & made a 55Kg Bull Arab VERY sick with a subsequent strike (they strike "dry" first).
If you're considering coming back down here for a vacation (or to live), you should understand that anyone who can directly trace their lineage back to an original convict is considered Australian "Royalty". I've got a mate who's originally from Texas. 'Told me he originally had a hard time getting to grips with the irreverant Aussie sense of humour/vernacular etc., but now always greets me with a smile, a hug & "G'Day dog's-breath"