The Pacific is the largest and deepest of all the oceans with an area of 165 million square kilometres, an area greater than that of all the world's lands put together. At its greatest width the Pacific measures 17,220km. It extends from the Bering Straits of the Arctic Circle, to Cape Adare, Antarctica, a distance of 15,450km. There are very few islands in the eastern Pacific. Its northern and western borders are fringed with chains of islands including The Aleutians, The Kurils and the Ryukus. The Inner Pacific islands are divided into three main groups - Melanesia, Micronesia and Polynesia.