Australia is the sixth largest country and smallest continent, surrounded by the Pacific Ocean, Indian Ocean, Timor Sea, Gulf of Carpentaria, and Arafura Sea. The landmass contains three main areas - the Eastern Highlands, Central Lowlands, and Western Plateau. It has the highest peaks on the continent like Mount Kosciuszko and the lowest point at Lake Eyre which is 15 meters below sea level. Australia is also home to the largest 'rock' in the world, Mount Augustus, which is twice the size of Uluru and over 1.65 billion years old. The five major rivers are the Murray, Murrumbidgee, Darling, Lachlan, and Cooper Creek,