i worked in Geikie Gorge (Kimberley) for about 6 mths. (thats in WA for everyones benefit...

)
swam in the gorge every day. the boat tour was very informative, about 900 crocs lived in there, all freshies.
as far as i knew at the time, with locals swimming there every day for 6 months of the year, there had never been a croc attack.
yes, at first it was unnerving seeing crocs a hundred metres away while swimming, but once you understand the animal and its behaviour and preferences it was no concern. fyi, if a freshie bites you and tries to roll you it is likely to break its jaw and then die a slow starving death. they know not to snack on too big a meat source.