We get the Red back spider here, if you get an outside shed, then they'll love the dark corners or under the rims of your wheelie bin, they are the most common deadly one, but really only deadly to the old or young. The truth is as well they are very timid and will run rather than bite..
The scary one is the huntsman, they're massive, yet harmless, in fact they get all the other ones for you, so handy to have in the garden.
Off the coast there is always the risk of Great White sharks, in our first summer here 2 people died from attacks. Not trying to be scary, but if you swim in the safe areas and the helicopters are flying over head you are perfectly safe...
The great white often mistakes surfers for seals they are so misunderstood yet fascinating.
What do the helicopters do are they on shark patrol?