Freezer Suits on the Sunshine Coast!!!!!! Us mad folk down here would probably be out in thongs and shorts in your 'cold' weather
Next couple of months is ideal time for snorkling off Bundaberg coastline - calm clear waters. After years living in Melbourne, I'd return and hit the water just after sunrise to get the calmest conditions. Forgot my shorty wetsuit one morning but could still spend a hour in the water