Am pretty sure Air Whitsundays are not currently doing endorsements and Akuna is no longer operating so the net aint that good for current up to date info (word on the street is that Akuna are trying to get Port Macqaurie operation back up and running but not sure if/when that will happen)....at the moment Gold coast is about closest to Cairns that you might be able to obtain a float endorsement...try cloud nine seaplanes (staright float 185) or maybe gold coast seaplanes (amphib beaver)