Palau's most populous islands are Angaur, Babeldaob, Koror and Peleliu. The latter three lie together within the same barrier reef, while Angaur is an oceanic island several miles to the south. About two-thirds of the population live on Koror. The coral atoll of Kayangel is north of these islands, while the uninhabited Rock Islands (about 200) are west of the main island group. A remote group of six islands, known as the Southwest Islands, some 375 miles (604 km) from the main islands, make up the states of Hatohobei and Sonsorol.