Why is Australia called the smallest continent?

Answer 1

Because either it is a whopping big island, or it's a small continent. And the decision was made to treat it as a big continent.

Further information:

Geographically, Australia is classed as a continent, not an island, for a number of specific reasons. As a landform, it could be considered an island as it is entirely surrounded by water and not joined onto any other land mass, and for this reason, it is often referred to as an island continent. Australia is too big to be formally classified as an island. The world's largest island is Greenland.

Another reason why Australia is also considered a continent is because it sits on its own tectonic plate. This is different from Greenland, which uses the same land mass as North America. That is why the geological appearances are much different in Australia from anywhere else. A place like Greenland shares the same geologic attributes as North America.

Australia and Antarctica are the only two true Continental Islands. That is, they are separated from all other continents by water. All other continents are connected by a landmass to at least one other Continent. If there are any waterways, they have been artificially created.

Answer 2

Australia is made up of six states and two mainland territories. The smallest territory is the Australian Capital Territory, or ACT, while the smallest state is Tasmania.