This extreme adventure begins more than 40 million years ago when Australia was part of the super continent of Gondwana. As this huge landmass broke up, Australia drifted north into the warm waters of the Pacific Ocean, as its sister continent, Antarctica, remained trapped at the South Pole. Nestled in the Earth's southern hemisphere, Australia is comparable in size to the United States and is the largest island in the world. Isolated from the other continents for millions of years, its plants and animals evolved in a unique way. To some it may appear to be more like another planet than another continent.