Dick,
There is a huge difference in how low level flight is treated between the USA and Australia. In the USA you can fly below 500 feet as long as you are not closer than 500feet to any person, vessel, vehicle or structure. You do not need a reason to be doing it you can. If you want to cruise up the coast of the Outer Banks of North Carolina at 50feet go for it as long as there aren't any cars(or people) on the beach.
The Australian rules are far more restrictive.
CIVIL AVIATION REGULATIONS 1988 - REG 157 Low flying