Australia is unique in the world of geography for being the only nation that is also considered a continent. While it is the smallest of the seven continents, it is the sixth-largest country by total area. Because it is surrounded by the Indian and Pacific Oceans, it is often referred to as an 'island continent.' This isolation has led to the evolution of unique flora and fauna found nowhere else on Earth, such as kangaroos and koalas. Geologically, Australia sits in the middle of its own tectonic plate, making it one of the most geologically stable continents with relatively little volcanic or seismic activity compared to its neighbors in the Ring of Fire.