Cairns is probably the first city that people think of as far as getting to the Barrier Reef goes. Check the map - there are alternatives. From Bundaberg in the south to Cooktown in the far north there are cities providing boat trips to reef areas.
As one goes further north the distance to the outer reef decreases. This puts Cairns in the prime position for day trips to the reef.
Cairns ClimateKeep in mind the the
Beach Nasties in Tropical Queensland.
Nov 2007 PREDICTION OF STINGER NUMBERSBrisbane is just too far south so don't turn up there expecting to "go for an afternoon drive to see the GBR".
By the way
the most dangerous physical activity that you can indulge in while in Cairns has nothing to do with adventure sailing, snorkeling, rafting , or swimming with sharks, stingers, or stingrays.
It's more mundane than those activities