Mainland Australia is the world’s largest island - but smallest continent. It is sometimes informally referred to as an 'island' continent, surrounded by oceans. Australia also has one of the most urbanized and coast-dwelling populations in the world, with more than 80 percent of residents living within 100 kilometers of the coastline. Australia currently has a population of almost 23 million people. Australia is known for its gorgeous beaches, the Great Barrier Reef, koalas and kangaroos.